CN1810911B - Raw material for cerium-based abrasive and method for producing raw material for cerium-based abrasive, cerium-based abrasive and method for producing cerium-based abrasive - Google Patents

Abstract

The present invention relates to a cerium-based abrasive comprising a carbonate-containing rare earth compound having a cerium oxide content of at least 30% by mass relative to total rare earth oxides (TREO) and a fluorine concentration of at most 0.5% by mass relative to TREO As a raw material, the sedimentation volume when the raw material slurry mixed with pure water to a TREO concentration of 126 g/L was left to stand for 10 minutes was 30 mL or more relative to 100 mL of the raw material slurry. In addition, the apparent specific volume by static method after drying at 120° C. for 12 hours is preferably 1.0 to 3.0 mL/g, and the content of hexane-extracted substances measured when dissolved in hydrochloric acid is preferably expressed on the basis of TREO. It is 700 mass ppm or less.

Description

Raw material for cerium-based abrasive and method for producing raw material for cerium-based abrasive, cerium-based abrasive and method for producing cerium-based abrasive

technical field

The present invention relates to a raw material for cerium-based abrasives, a method for producing the same, and a cerium-based abrasive produced from the raw material for cerium-based abrasives.

Background technique

Cerium-based abrasives (hereinafter sometimes simply referred to as abrasives) are abrasive particles composed of cerium oxide (CeO ₂ ) particles as the main component and other rare earth metal oxide particles, and are currently used for grinding various glass materials. In particular, it has recently been used to polish glass materials used in electrical and electronic equipment such as glass for magnetic recording media such as hard disks, and glass substrates for liquid crystal displays (LCD), and its application range is expanding.

As a method for producing cerium-based abrasives, first, pulverize the raw materials for abrasives, perform chemical treatment as needed, then heat and roast at high temperature to sinter the raw material particles, and then pulverize them again to produce cerium-based abrasives with desired particle size and particle size distribution. abrasive.

Here, as a raw material of cerium-based abrasives, a natural raw material called bastnaesite concentrate obtained by beneficiating a rare earth ore called bastnaesite is generally used at present. However, in recent years, due to concerns about environmental issues and in order to improve the performance of the prepared abrasives, recently, the raw materials for abrasives that have been separated and extracted from bastnaesite and cheap Chinese-made compound ores are gradually used.

For example, Japanese Patent Application Laid-Open No. 2004-2870 discloses a light rare earth raw material mainly composed of cerium in which the content of alkali metals, alkaline earth metals, and radioactive substances is reduced. This raw material for abrasives solves environmental problems by removing radioactive substances and fluorine contained in bastnaesite, and improves the performance of abrasives by removing alkali metals and alkaline earth metals that cause grinding damage when used as abrasives.

In addition, the present applicant has disclosed a polishing raw material described in Japanese Patent No. 3365993 as a polishing raw material excellent in both polishing force and polishing precision. The raw material for grinding is obtained by calcining rare earth compounds (cerium rare earth carbonates) produced from bastnaesite, etc., and converting a part of them into cerium rare earth oxides. A raw material for cerium-based abrasives with a strong heat loss of 0.5-25% when heated at °C for 1 hour.

However, it is desired not only for cerium-based abrasives but for all abrasives to realize high-precision polishing surfaces at high polishing speeds without damaging the polishing surface. In particular, cerium-based abrasives have been increasingly used for grinding glass for magnetic recording media as described above, and there is a great demand for them.

However, although the raw materials for abrasives described in the above-mentioned Patent Document 1 can solve environmental problems, the abrasives produced therefrom have a low polishing rate and cannot effectively suppress the occurrence of grinding damage. In addition, compared with the raw materials described in Patent Document 1, the raw materials described in Patent Document 2 can produce abrasives with excellent polishing speed and polishing surface accuracy at low cost. However, with the increase in density of recording media such as hard disks and the increase in precision and precision of LCD panels, there has been a need for abrasives for processing and polishing that can form the above-mentioned high-precision grinding surface. Therefore, it is necessary to further improve the abrasive raw material.

The present invention was made under the above background, and is a raw material suitable for cerium-based abrasives, and its object is to provide a raw material for producing abrasives capable of maintaining a polishing speed and forming a high-precision grinding surface. In addition, the purpose is to clarify the production method of such a raw material for abrasives.

Contents of the invention

In order to solve the above-mentioned problems, the present inventors studied the relationship between various characteristics of raw materials for cerium-based abrasives and polishing characteristics when used as abrasives. Then, the present invention was conceived by focusing on the relationship between the sedimentation volume, which is a characteristic of slurrying raw materials mixed in water, and the grinding properties of the abrasive.

That is, the present invention relates to cerium containing a carbonate-containing rare earth compound having a cerium oxide content of at least 30% by mass relative to total rare earth oxides (TREO) and a fluorine concentration of at most 0.5% by mass relative to TREO. It is a raw material for abrasives, and it is a raw material for cerium-based abrasives whose sedimentation volume is 30 mL or more when the raw material slurry mixed with pure water to a TREO concentration of 126 g/L is left to stand for ten minutes relative to 100 mL of the raw material slurry.

The reason why the settling volume of the abrasive raw material is 30 mL or more relative to 100 mL of the raw material slurry is that if it is less than 30 mL, the grinding accuracy of the prepared abrasive will decrease, and there will be a problem of grinding damage. On the other hand, from the viewpoint of polishing accuracy, there is no particular limitation on the upper limit of the sedimentation volume, but if the sedimentation volume is too large, the polishing speed will decrease, making it impossible to perform efficient polishing. Therefore, taking these points into consideration, the sedimentation volume is preferably from 30 to 90 mL, more preferably from 30 to 70 mL, further preferably from 40 to 60 mL.

In addition, the reason for determining the sedimentation volume of the present invention as a slurry concentration of 126 g/L is as follows, that is, when it is a typical raw material for cerium-based abrasives (TREO45% by mass), the mass ratio of the raw material and water is 1. 3 Mixed slurries, it has been confirmed that the difference in sedimentation volume caused by the raw material is easy to occur, and as a result, it is easy to understand the difference in the sedimentation volume of the raw material and the performance of the produced abrasive. Therefore, the TREO concentration of the slurry in which the raw material and water were mixed at a mass ratio of 1:3 was about 126 g/L. However, the raw material for abrasives according to the present invention contains water, and it is difficult to make the TREO concentration of the slurry exactly 126 g/L. Therefore, in fact, with the TREO concentration reaching 126g/L as the target, making it within the range of 126 ± 5g/L, the error of the measured sedimentation volume can be reduced, and it can be used as an evaluation standard for abrasive raw materials. value.

As a method of measuring the sedimentation volume, a raw material for cerium-based abrasives and pure water were mixed, a raw material slurry was prepared so that the concentration of TREO was 126 g/L, and the raw material slurry was obtained by mixing well. A 100 mL graduated cylinder was then filled with the stock slurry up to the 100 mL mark. Read the interface between the precipitate and the liquid after 10 minutes, and the volume occupied by the precipitate is the sedimentation volume. In addition, as the above-mentioned 100 mL measuring cylinder, a volume meter of class A or class B described in JIS R3505-1994 "Volume meter made of glass" or a volume meter with equivalent or higher accuracy can be used. Either a non-tie type or a plug-in type may be used. In addition, the temperature for measuring the sedimentation volume is preferably at a constant temperature in the range of 10 to 50°C, more preferably at a constant temperature in the range of 15 to 40°C, and still more preferably at a constant temperature in the range of 20 to 30°C. When preparing a raw material slurry B mL with a TREO concentration of 126 g/L from an abrasive raw material with a TREO content rate A (mass %), the amount C (g) of the abrasive raw material used can be calculated according to the following calculation formula.

Formula 1

C×A÷100＝126×B÷1000

C＝12.6×B÷A

A is the TREO content (% by mass) of the raw material for abrasive, B is the adjusted amount (mL) of the raw material slurry, and C is the amount (g) of the raw material for abrasive used.

In addition, the TREO content rate A of the raw material can be obtained by measuring the TREO of the raw material, but the measurement of TREO takes time and effort. Therefore, the intense heat loss D (mass %), which is easier to measure than TREO, can be measured and obtained from A=100-D.

The raw material for abrasives according to the present invention preferably has an apparent specific volume at rest after drying at 120° C. for 12 hours of 1.0 to 3.0 mL/g. This is because the average surface roughness (Ra) of abrasives made of raw materials with too small apparent specific volume will increase. On the other hand, the grinding speed of abrasives made of raw materials with too large apparent specific volume will decrease. the trend of. The apparent specific volume is a value obtained in accordance with "20.1 Standing method" of "20. Apparent density or apparent specific volume" in JIS K501-1991 (pigment test methods). The preferable range of the apparent specific volume is 1.3-2.7L/g, and the more preferable range is 1.5-2.5mL/g.

The measurement object of apparent specific volume is through drying, and this is because most of the raw materials for abrasive materials involved in the present invention contain moisture. If the apparent specific volume is directly measured, the measured value will fluctuate, and it will be difficult to measure especially when the amount of water is very large. , so it cannot be used as a criterion for judging whether it is suitable as a raw material for abrasives. Therefore, in order to fully remove water, it should be dried at 120°C for 12 hours.

In the raw material for abrasive according to the present invention, the content of cerium oxide relative to TREO must be at least 30% by mass, preferably at least 50% by mass. The content of cerium oxide in the raw material directly reflects the content of cerium oxide in the abrasive, which can affect the grinding speed of the abrasive. When the content of cerium oxide in the raw material is less than 30% by mass, the polishing rate of the obtained abrasive will decrease. Also, the upper limit of the cerium oxide content is not particularly limited, but it is preferably 99.9% or less from the viewpoint of raw material cost.

In addition, the fluorine concentration in the raw material must be at most 0.5% by mass relative to TREO, preferably at most 0.2% by mass, more preferably at most 0.1% by mass. This is because, of course, it is preferable to reduce the fluorine in the raw material when producing an abrasive grain to which no fluorine component is added, from the viewpoint of the above-mentioned environmental problems related to fluorine. In addition, it is also because it is easier to use a raw material with a lower fluorine concentration than to suppress the amount of fluorine even when adding a fluorine component to manufacture an abrasive.

"Contains a carbonate group" in the present invention clarifies that the abrasive raw material according to the present invention is a raw material containing a cerium-based rare earth carbonate. The raw material for abrasives according to the present invention may partially contain monohydroxycarbonates, hydroxide carbonates, hydroxides, and oxides.

The raw material for the abrasive according to the present invention is preferably a raw material having a reduced chlorine concentration, specifically, the chlorine concentration is preferably at most 0.5% by mass (TREO standard), more preferably at most 0.3% by mass, more preferably at most 0.1% by mass . This is because if chlorine is contained in the raw material for abrasives, the polishing rate when used as an abrasive tends to decrease.

The strong heat loss when the raw material for abrasive is heated at 1000° C. for 1 hour is preferably at least 20%. Intensive heat loss refers to the rate of mass loss when an object is subjected to intense heat. In the present invention, the strong heat loss is 20 mass% or more because if the strong heat loss is less than 20 mass%, the carbonate content in the raw material is reduced. The effect will not meet the requirements. Therefore, for this reason, the value of the strong heat loss is preferably large, more preferably at least 35% by mass, and still more preferably at least 50% by mass. In addition, although the upper limit is not particularly limited, if the heat loss is too high, since the transportation cost will increase, it is preferably at most 90% by mass, more preferably at most 70% by mass, even more preferably at most 70% by mass. 60% by mass or less.

In addition, as a measurement method for strong heat loss, add raw materials for abrasives to a crucible whose mass has been measured in advance. After measuring the total mass, heat it in a furnace at 1000°C for 1 hour, then cool it in a dry atmosphere, and then measure it. The mass of the crucible can be calculated according to the following calculation formula for strong heat loss. In addition, when the raw material contains a lot of water, such as rapid and strong heating at 1000°C for 1 hour, the correct measurement may occur due to the raw material blowing to the outside of the crucible. Add raw materials for abrasives into a good quality crucible, and after measuring the total mass, heat it at 100-150°C to reduce the water content and then carry out strong heating.

Formula 2

B=(W ₁ -W ₂ )/(W ₁ -W ₃ )×100

B: Strong thermal loss (%), W ₁ : Mass of abrasive material and crucible before heating (g), W ₂ : Mass of abrasive material and crucible after heating (g), W ₃ : Mass of crucible .

In addition, the raw material for abrasives according to the present invention preferably has a content of hexane-extracted substances measured when dissolved in hydrochloric acid in terms of TREO, and is preferably at most 700 mass ppm. This hexane-extracted substance does not directly affect the abrasive properties when the raw material becomes an abrasive. However, if there are too many hexane-extracted substances, it becomes difficult to see the interface when measuring the sedimentation volume of the raw material for abrasives, so it is preferable that there are few hexane-extracted substances. The hexane-extracted substance is preferably at most 700 mass ppm, more preferably at most 250 mass ppm, still more preferably at most 150 mass ppm.

The method of measuring the content of hexane extracts is to dissolve the raw materials for abrasives in hydrochloric acid, and measure hexane in accordance with "24.2 Extracts of hexane" in "24. Calculated from the amount of alkane extractable substance. That is, in hydrochloric acid, dissolve the abrasive raw material D (g) of TREO content rate A (mass %), if the amount of the hexane-extracted substance measured by this liquid is recorded as E (mg), then the abrasive raw material The hexane-extracted substance (ppm by mass) based on TREO is E×1000÷(D×A÷100).

In the method for producing the raw material for abrasives according to the present invention, the sedimentation volume of the raw material to be produced must be within a predetermined range during slurrying. The inventors mixed an aqueous solution of at least one carbonate-based precipitant selected from alkali metal carbonates, alkali metal bicarbonates, ammonium carbonate, ammonium bicarbonate, guanidine carbonate, ammonium carbamate, and urea with an aqueous solution containing a rare earth compound. Aqueous solution, which can be used to manufacture raw materials for abrasives with controlled sedimentation volume.

What is important here is the order of mixing the aqueous solution of the carbonate-based precipitant and the aqueous solution containing the rare earth compound. The raw material for abrasives according to the present invention must have a sedimentation volume of 30 mL (relative to 100 mL of the raw material slurry) or more. No matter how the mixing order of these aqueous solutions is, the inventors can produce the raw materials with increased sedimentation volume, and the situation of adding the aqueous solution containing rare earth compounds in the aqueous solution of the carbonated precipitating agent after stirring (hereinafter, for the sake of simplicity, will be referred to as Mixing according to this order is the reverse addition method), regardless of the stirring speed of the aqueous solution of the carbonic acid-based precipitating agent, a raw material with an increased sedimentation volume can be produced.

That is, for the 1st method of the raw material for the abrasive material that the present invention relates to, stir at least An aqueous solution of a carbonic acid-based precipitating agent, which is mixed with a cerium oxide content of 30% by mass or more relative to the total rare earth oxides (TREO), a fluorine concentration of 0.5% by mass or less with respect to the TREO, and The aqueous solution of the rare earth compound of the carbonate group generates a precipitate, and then separates and washes the precipitate.

On the other hand, the reverse mixing order of the above-mentioned reverse addition method, that is, the case of stirring the aqueous solution containing the rare earth compound and adding the aqueous solution of the carbonic acid-based precipitating agent (hereinafter, for the sake of simplicity, the mixing in this order is referred to as positive In the addition method), the aqueous solution of the rare earth compound is stirred at a rapid stirring speed, specifically more than 100 m/min, and a raw material with an increased sedimentation volume can be produced.

That is, the second method for producing the raw materials for abrasives according to the present invention includes the steps of stirring the content of cerium oxide to 30% by mass relative to the total rare earth oxides (TREO) at a peripheral speed of 100 m/min or more. % or more, and the fluorine concentration is 0.5% by mass or less relative to TREO, an aqueous solution of a rare earth compound, %% is added to the above rare earth compound aqueous solution , guanidine carbonate, ammonium carbamate and an aqueous solution of at least one carbonic acid-based precipitating agent in urea to generate a precipitate, and then separate and wash the above-mentioned precipitate.

Hereinafter, the manufacturing method of two kinds of raw materials for abrasive grains concerning this invention is demonstrated. As long as there is no special mark, the following descriptions are applicable to both the reverse addition method and the forward addition method. For the method involved in the present invention, two aqueous solutions, an aqueous solution of a carbonate-based precipitating agent and an aqueous solution containing a rare earth compound, are first prepared.

The aqueous solution containing rare earth compounds can be produced as follows, such as sulfuric acid decomposition method, alkali decomposition method can be used to decompose cerium-containing rare earth concentrates such as cerium lanthanum concentrate and bastnaesite concentrate, and then carry out precipitation, dissolution and other treatments respectively. Reduce and remove impurities such as uranium, thorium, calcium, barium, iron, phosphorus, etc., and then use solvent extraction to improve the quality of TREO standard cerium oxide if necessary. In addition, the rare earth chloride obtained by boiling the hydrochloric acid-based rare earth compound aqueous solution obtained in this way, cooling and solidifying can be dissolved in water or dilute hydrochloric acid. It is also possible not to use the above-mentioned natural cerium-containing rare earth concentrates as starting materials, but to use pre-made rare earth compounds such as rare earth chlorides and cerium-based rare earth carbonates, and dissolve them in acids such as hydrochloric acid, A solution with an appropriately adjusted composition was used as the starting material. At this time, even if the content of cerium oxide is outside the content range described in the present invention (less than 30% by mass), after dissolution with acid, the content of cerium oxide based on TREO can be increased by using solvent extraction or the like. used in the present invention.

In addition, in order to produce the abrasive material having a fluorine concentration of 0.5% by mass or less relative to TREO, it is of course necessary to use an aqueous solution of a rare earth compound having a fluorine concentration of 0.5% by mass or less relative to TREO. However, the fluorine-containing rare earth compound solution generates precipitates of fluorinated rare earth compounds in the solution, and the fluorine concentration of the rare earth compound containing no solid content is 0.5% by mass or less relative to TREO. Even if it is a rare earth aqueous solution containing solid content (that is, a rare earth compound solution containing fluorine), the solid content can be removed by filtration or the like to obtain a rare earth compound aqueous solution with a fluorine concentration of 0.5% by mass or less relative to TREO.

The concentration of the rare earth compound in the rare earth compound aqueous solution is preferably from 10 to 250 g/L, more preferably from 20 to 200 g/L, based on TREO. When the concentration of the rare earth compound is too low, a large amount of solution is required, which is not suitable from the viewpoint of wastewater treatment. On the other hand, when the concentration of the rare earth compound is too high, the reaction to produce precipitation tends to be uneven, and coarse particles may be generated.

In addition, as can be understood from the above description, the rare earth compounds in the rare earth compound aqueous solution used in the present invention are exemplified chlorides, nitrates, sulfates, perchlorates, etc., but the rare earth compound aqueous solution used in the present invention It is preferably an aqueous solution in which chloride exists as a rare earth compound. When the raw material is produced from an aqueous chloride solution, there may be residual chlorine, but the residual chlorine can be easily disposed of by sufficiently performing cleaning in the subsequent cleaning step. In this regard, when using an aqueous solution in which nitrate exists as a rare earth compound, considering the latest nitrogen regulations, expensive wastewater treatment must be required to remove residual nitrogen.

An aqueous solution of a carbonate-based precipitating agent can be produced by mixing water (pure water) with a carbonate-based precipitating agent. The carbonate-based precipitant is a precipitant containing at least one selected from the group consisting of alkali metal carbonates, alkali metal bicarbonates, ammonium carbonate, ammonium bicarbonate, guanidine carbonate, ammonium carbamate, and urea. As the alkali metal in the alkali metal carbonate and the alkali metal bicarbonate, sodium, potassium, and lithium are suitable. From the viewpoint of not mixing alkali metals into the precipitate, the carbonate-based precipitating agent is preferably a precipitating agent not containing an alkali metal, and ammonium bicarbonate is preferred among them. The concentration of the carbonate-based precipitant is preferably from 0.2 to 1.0 mol/L. At this time, if it is less than 0.2 mol/L, the discharge rate will increase, and if it exceeds 1.0 mol/L, the reaction may not be uniform. The usage amount of the carbonic acid-based precipitant aqueous solution is determined by the usage amount of the rare earth compound aqueous solution (related to the production amount as the target raw material). With respect to the rare earth element and excess acid in the rare earth compound aqueous solution, the amount of the carbonic acid precipitating agent is 0.95 to 2.5 times (preferably 1.0 to 2.0 times, more preferably 1.1 to 1.5 times) the stoichiometric amount, It is preferred to determine the usage-amount of the aqueous solution in consideration of the concentration of the carbonic acid-based precipitating agent based on this amount. If it is less than the lower limit, the yield will decrease because the precipitation of rare earth elements cannot be sufficiently formed. In addition, the amount of excess acid in the rare earth compound aqueous solution can be determined, for example, by neutralization titration using bromocresol green methyl red as an indicator. However, when the pH of the rare earth compound aqueous solution is above 1 (especially above 2), since the amount of excess acid is very small, even negligible has no effect.

Precipitation is produced by mixing the prepared aqueous solution of the carbonate-based precipitant and the aqueous solution of the rare earth compound. Here, the reverse addition method and the forward addition method refer to the difference in stirring objects and mixing order. In the reverse addition method, an aqueous solution of a carbonate-based precipitating agent is stirred, and an aqueous solution of a rare earth compound is added thereto, and the stirring speed at this time is not particularly limited.

On the other hand, the positive addition method is to add the aqueous solution of the carbonic acid-based precipitating agent while stirring the rare earth compound aqueous solution. 100m/min or more. This is because there is a high possibility that a raw material for abrasives having a sedimentation volume of less than 30 mL will be produced when stirring at a stirring speed lower than this speed. The stirring speed in the positive addition method is preferably at least 125 m/min, particularly preferably at least 150 m/min. The upper limit of the stirring speed is not particularly limited, but considering the cost of the stirring device, it is at most 4000 m/min, preferably at most 3000 m/min, more preferably at most 2000 m/min.

The addition time of the aqueous solution of the rare earth compound or the aqueous solution of the carbonate-based precipitating agent is preferably from 5 to 1200 minutes, more preferably from 10 to 600 minutes, still more preferably from 20 to 300 minutes. If it is added too quickly, the resulting precipitate will be in the form of fine particles, and the grinding speed of the prepared abrasive will decrease. At the same time, the generated precipitate will be uneven, and the grinding accuracy of the obtained abrasive will also decrease a little. On the other hand, if it is added too slowly, coarse precipitates will also be generated, and the grinding accuracy of the prepared abrasive will also decrease. In addition, although it is not particularly necessary to heat the solution at the time of mixing, it may be heated. At this time, the liquid temperature is preferably at most 60°C, particularly preferably at most 40°C. If the temperature of the solution is too high, the precipitate will become coarse, and the grinding precision of the prepared abrasive will decrease.

The raw material for abrasives of the present invention can be obtained by solid-liquid separation and washing of a precipitate formed by mixing the above-mentioned aqueous solution of the carbonic acid-based precipitating agent and the aqueous solution of the rare earth compound. The raw material for abrasives after cleaning may also be suitably dried.

In addition, as described above, the abrasive of the present invention preferably has a content of hexane-extracted substances measured when dissolved in hydrochloric acid of 700 mass ppm or less on the basis of TREO. The hexane-extracted substance is derived from an organic solvent used for solvent extraction that is often performed in the production process of abrasive raw materials. As a method for reducing hexane-extracted substances, Method 1 is a method of statically containing an aqueous rare earth compound solution containing hexane-extracted substances, and separating and removing the hexane-extracted substances in the aqueous solution. In addition, method 2 is a method in which an aqueous solution of a rare earth compound containing a hexane-extracted substance is brought into contact with an oil adsorbent such as polypropylene fiber, plant fiber, or activated carbon, and the hexane-extracted substance is adsorbed and removed. It is preferable to carry out at least any one of these steps for removing hexane-extracted substances, but carrying out the above-mentioned method 2 after method 1 can significantly improve the effect.

In addition, in order to reduce hexane-extracted substances, regardless of either of the above-mentioned methods 1 and 2, the one with a lower pH is more efficient. Specifically, the pH of the rare earth compound aqueous solution is preferably at most 3.0, more preferably at most 2.0, and even more preferably at most 1.0. However, if the pH is too low, although it is preferable from the viewpoint of removing hexane-extracted substances, a large amount of precipitating agent must be required. Therefore, the lower limit of the pH of the aqueous rare earth compound solution subjected to the hexane-extracted substance reduction treatment is preferably at least 0.0, more preferably at least 0.2.

To manufacture cerium-based abrasives from the raw material for abrasives of the present invention, the methods commonly used at present can basically be adopted. That is, after pulverizing the raw material for abrasives, the abrasives can be produced by roasting and proper pulverization and classification.

Here, as the pulverization step of the abrasive raw material performed before the firing step, it can generally be performed using a pulverization device, particularly a wet pulverization device. However, as a more effective pulverization method, it is also possible to mix the raw materials for abrasives in an aqueous solution containing at least one compound selected from ammonia, ammonium carbonate, ammonium bicarbonate, guanidine carbonate, ammonium carbamate, and urea or in water. , heated at 60 to 100° C., and then pulverized the abrasive material (hereinafter, this pulverization method is referred to as immersion heating pulverization.). The abrasive produced by performing this immersion heating pulverization is an abrasive that can form a grinding surface with less grinding damage and higher precision. The time for the immersion heating pulverization is not particularly limited as long as it is before firing. However, performing immersion heating and pulverization does not prevent pulverization using a pulverization device. Therefore, these two pulverization methods can be suitably combined and implemented.

As mentioned above, compared with the abrasive produced by using the current raw materials for cerium-based abrasives, the use of the raw materials for cerium-based abrasives of the present invention can produce not only the same or higher polishing speed, but also cerium-based abrasives that can form higher-precision grinding surfaces. abrasive. Since the raw material for abrasives according to the present invention does not contain fluorine at all by its nature, it can solve environmental problems and recycle abrasives. In addition, although the raw material for abrasives of the present invention is particularly useful for producing abrasives without adding fluorine, it can also be used for producing abrasives by adding fluorine components while adjusting the concentration of fluorine components.

Description of drawings

FIG. 1 is a diagram briefly explaining manufacturing steps 1 and 2 of an aqueous solution containing a rare earth compound in the present embodiment.

Detailed ways

Hereinafter, preferred embodiments of the present invention will be described. This embodiment is a method of mixing a carbonic acid-based precipitant aqueous solution and a rare earth compound to produce a raw material for abrasives, using different starting materials to prepare a variety of rare earth compound aqueous solutions through various processes, and then adding and mixing them to the carbonic acid-based precipitation. It can be used to manufacture a variety of raw materials for abrasives in aqueous solution. These were then used to produce cerium-based abrasives, and the grinding properties of these cerium-based abrasives were evaluated.

A: Manufacture of rare earth compound aqueous solution

A plurality of rare earth compound aqueous solutions were produced through the following two production processes.

Manufacturing process 1

In this production process, a rare earth compound aqueous solution is produced using rare earth chloride as a starting material. The raw material for abrasives obtained from the rare earth compound aqueous solution produced through this manufacturing process is suitable for Examples 1-30, 36-44, and Comparative Examples 1, 2, and 4 mentioned later. The outline of this manufacturing process is shown in FIG. 1( a ).

Rare earth chloride (TREO46% by mass) was dissolved with 0.3 mol/L hydrochloric acid to prepare a solution having a TREO concentration of 150 g/L, and the solution was extracted with a solvent. Solvent extraction is carried out in a mixed clarifier with 30 sections (10 sections for convective extraction and 20 sections for countercurrent extraction) (the effective capacity of the clarified part is 200 L/section). The organic solvent enters from the first section of the extraction section and flows out from the 10th section at a capacity of 6L/min, and then directly enters from the first section of the reverse extraction section and flows out from the 20th section. The solution in the water phase enters from the 10th section of the extraction section at a rate of 1 L/min, and 2 mol/L of hydrogen is added to the 1st, 3rd, 5th, and 7th sections of the extraction section at a rate of 0.35 L/min. Sodium oxide aqueous solution, and make it flow out from the first stage of the extraction part. In the back extraction section, inject 5.2mol/L hydrochloric acid at 1L/min from the 20th section of the back extraction section, extract from the 11th section at 0.56L/min, and extract the residue from the first section of the back extraction section. Sodium hydroxide is added to extract almost all the rare earth elements in the solution into the organic solvent. In addition, the organic solvent is a solvent obtained by mixing an extractant (PC-88A (manufactured by Daihachi Chemical Industry Co., Ltd.)) and a diluent (IP Solvent (manufactured by Idemitsu Petrochemical Co., Ltd.)) at a volume ratio of 1:2.

Next, the pH of the back extract liquid (TREO concentration: 291 g/L) extracted from the first stage of the back extraction part of the solvent extraction process was adjusted to pH = 0.9 with hydrochloric acid, and it was left to stand for 24 hours for oil-water separation ( Stand still for 3 hours in embodiment 22, do not carry out oil-water separation in embodiment 21,24.).

The reverse extract after the above-mentioned treatment was passed through a column filled with polypropylene fibers for adsorbent treatment (the adsorbent treatment was not performed in Examples 21 to 23).

The concentration of the reverse extraction solution (rare earth compound aqueous solution) after the above treatment is properly adjusted with pure water to prepare an aqueous solution of rare earth compound with a TREO concentration of 5-270 g/L. In addition, in the above process, the composition in TREO contained in the rare earth chloride (solution solution) before treatment and the composition in TREO contained in the reverse extraction solution (rare earth compound aqueous solution) after solvent extraction are as follows. In addition, the amount of rare earth elements per 1 kg of TREO in the prepared rare earth compound aqueous solution was 5.92 mol.

Table 1

Manufacturing process 2

In this production process, a rare earth compound aqueous solution was produced using Chinese cerium carbonate (TREO45 mass%, CeO ₂ /TREO>99.9 mass%: an abrasive raw material composed of this cerium carbonate was used as Comparative Example 3). Raw materials for abrasives obtained from the rare earth compound aqueous solution obtained in this production process were used in Examples 31 to 35 described later. The outline of this manufacturing process is shown in figure (b).

Dissolve the above-mentioned cerium carbonate with 0.2 mol/L hydrochloric acid, and filter to prepare a solution with a TREO concentration of 180 g/L. The pH of the solution was adjusted with hydrochloric acid until pH = 0.9, and the solution was left to stand for 24 hours for oil-water separation.

The solution after the above-mentioned treatment was passed through a column filled with polypropylene fibers to perform an adsorbent treatment. The concentration of the solution treated with the adsorbent is properly adjusted with pure water to prepare an aqueous solution of rare earth compounds with a TREO concentration of 50 g/L. In addition, the cerium oxide concentration (CeO ₂ /TREO) in the rare earth compound aqueous solution is 99.9% by mass or more. In addition, the amount of rare earth elements per 1 kg of TREO in the prepared rare earth compound aqueous solution was 5.81 mol (calculated as CeO ₂ /TREO as 100% by mass).

B: Manufacture of aqueous solution of carbonate-based precipitant

The aqueous solution of a carbonate-based precipitant is prepared by dissolving a carbonate-based precipitant (ammonium bicarbonate or sodium carbonate) in water. The dissolved amount of the carbonate-based precipitant is 1.2 times the total amount of the stoichiometric amount of the rare earth element contained in the aqueous rare earth compound solution and the stoichiometric amount necessary to neutralize the excess acid obtained by neutralization titration . In addition, since the rare earth elements in the rare earth compound aqueous solution in each example are all trivalent, they are calculated as trivalent.

C: Mixing of rare earth compound aqueous solution and carbonic acid precipitant aqueous solution

Mixing rare earth compound solution and carbonic acid-based precipitant aqueous solution to generate precipitate, which is washed to make abrasive raw material.

In Examples 1 to 40, the reverse addition method was adopted, that is, while stirring the aqueous solution of the carbonic acid-based precipitating agent, the rare earth compound aqueous solution was added in an amount of 30 kg of TREO. As the addition time at this time, various addition times of 3 to 1200 minutes can be employed, and the stirring speed (peripheral velocity) of the aqueous solution is set to various speeds of 50 to 175 m/min. For solution heating at the time of addition, mixing can be performed both with heating (30 to 70° C.) and without heating. The solution after adding the rare earth compound aqueous solution was stirred for 30 minutes before starting the next filtration step.

On the other hand, in Examples 41 to 44 and Comparative Examples 1, 2, and 4, precipitation was formed by the positive addition method, that is, by adding a carbonic acid-based precipitant while stirring the aqueous rare earth compound solution. In this case, the stirring speed is also set to various speeds of 50 to 175 m/min.

In addition, regardless of the reverse addition method or the forward addition method in the above examples, as long as the stirring speed of the aqueous solution of the carbonic acid-based precipitating agent or the aqueous solution of the rare earth compound is not specially marked, it is 75 m/min.

D: solid-liquid separation, cleaning

In order to separate the precipitate formed by stirring the aqueous solution of the carbonate-based precipitating agent and the aqueous solution of the rare earth compound, the solution was vacuum filtered. The precipitate separated by filtration was washed and used as a raw material for cerium-based abrasives. This washing was performed 0 to 5 times with pure water at 100 L/time (only Comparative Example 7 was not washed (0 times)).

For the raw materials for cerium-based abrasives produced by the above process, the sedimentation volume, hexane extract content, TREO concentration, fluorine concentration, chlorine concentration, strong heat loss, and average particle diameter (D ₅₀ particle diameter) were measured. In the measurement of these characteristics, the measurement of sedimentation volume, apparent specific volume by standing method, content of hexane-extracted substances, and strong heat loss was carried out according to the above-mentioned measurement methods.

The fluorine concentration is determined by melting the abrasive with alkali, then extracting it with warm water, and using the fluoride ion electrode method for determination. The chlorine concentration was determined by Volhard titration after dissolving the abrasive in nitric acid. In addition, TREO used as a standard is measured by the gravimetric method by dissolving the abrasive with acid, adding bromic acid to the solution to form a precipitate, and burning the precipitate.

The average particle size ( _D50 particle size) is measured by measuring the particle size distribution using a laser diffraction and scattering method particle size distribution measuring device (manufactured by Horiba Manufacturing Co., Ltd.: LA-920), and by calculating the volume-based cumulative score. The 50% by mass diameter in the rate is carried out.

Tables 2 to 7 show various characteristics of various raw materials for abrasives produced in this embodiment.

Then, cerium-based abrasives were produced using the prepared raw materials for cerium-based abrasives. In the production process of the abrasive, first, the raw material for abrasive produced by heating and pulverizing is immersed. Immersion heating pulverization was carried out by mixing 30 kg of abrasive raw material TREO and 150 L of pure water in a tank with a capacity of 350 L, blowing in steam while stirring, maintaining the temperature for 3 hours after reaching 90°C, and then cooling.

The slurry after immersion heating and pulverization was filtered, dried at 150° C. for 48 hours, dry pulverized with a fine grinder, and then calcined. The firing conditions were 980°C (when CeO ₂ /TREO>99.9% by mass) and 1050°C (when CeO ₂ /TREO=60% by mass) for 24 hours.

After the roasting treatment, the roasted product was poured into pure water to form 64 L of slurry, and then wet pulverized. The wet pulverization was carried out 5 times with a bead mill using zirconia balls with a diameter of 1.00 mm. After filtering the slurry, it was dried at 150° C. for 48 hours, and then dry pulverized with a fine grinder to obtain a cerium-based abrasive.

Characteristic Evaluation of Abrasives

For each of the prepared cerium-based abrasives, the average particle size and BET surface area were measured, and a polishing test was performed to evaluate the polishing characteristics (polishing speed, polishing precision).

The measurement of the specific surface area by the BET method was performed in accordance with "(3.5) one-point method of 6.2 flow method" of JIS R1626-1996 (method for measuring specific surface area by gas adsorption BET method of fine ceramic powder). At this time, a mixed gas of helium as a carrier gas and nitrogen as an adsorbate gas was used. In addition, the measurement method of an average particle diameter ( _D50 particle diameter) is the same as the measurement method of a raw material.

For the grinding test, a grinding tester (HSP-2I type, manufactured by Taito Seiki Co., Ltd.) was used. This polishing tester is a machine for polishing a surface to be polished with a polishing pad while supplying a slurry-like abrasive to the surface to be polished. In this polishing test, abrasives and pure water were mixed to prepare 20 L of slurry abrasives with a TREO of 100 g/L. Then, in the grinding test, the slurry abrasive was supplied at a rate of 5 liters/minute, and the abrasive was recycled. In addition, the object to be polished is glass for a flat plate of 65 mmφ. Polishing pads are made of polyurethane. The pressure of the polishing pad against the abrasive surface was 9.8 kPa (100 g/cm ² ), the rotation speed of the polishing tester was set at 100 rpm, and the polishing time was 30 minutes.

Then, the polishing characteristics were evaluated. First, the reduction in glass weight was obtained by measuring the glass weight before and after polishing, and the polishing value was obtained based on this value. In this grinding test, this grinding value was used to evaluate the grinding speed. In addition, here, the polishing value when the sample obtained in Example 1 is used is used as a standard (100).

The surface to be polished of the glass obtained by grinding was washed with pure water, dried in a dust-free state, and then the grinding accuracy was evaluated. This evaluation was carried out by measuring the surface roughness of the polished surface of the glass after polishing using an atomic force microscope (AFM), and evaluating Ra (average surface roughness).

Tables 8 to 13 show the results of physical properties and polishing properties of the various abrasives produced.

Based on the physical properties (Table 2 to Table 7) of the raw materials for abrasives produced by the above-mentioned manufacturing processes and the grinding characteristics (Table 8 to Table 13) of the abrasives made from these raw materials for abrasives, the comparison is carried out as follows investigation.

Evaluation 1: Evaluation of sedimentation volume

Tables 8 to 11 are tables showing comparison results of characteristics of abrasives produced using abrasive raw materials having different sedimentation volumes produced by changing production conditions. The sedimentation volume of abrasive raw materials varies depending on the production conditions (concentration of the aqueous solution of rare earth compounds, addition time, number of washings of the precipitate) (this point will be described later), but in any case, the sedimentation volume is less than 30mL Abrasives prepared from raw materials for abrasives have high surface roughness and poor grinding accuracy (damages are confirmed to occur) although the grinding speed is high. Therefore, it is required that the sedimentation volume of the abrasive raw material must be 30 mL or more. On the other hand, the grinding speed of the abrasive produced from the raw material for abrasive with a sedimentation volume greater than 90 mL decreased. Therefore, in consideration of the balance between the grinding speed and the grinding precision, the sedimentation volume is preferably from 30 to 90 mL, more preferably from 30 to 70 mL, and still more preferably from 40 to 60 mL.

In addition, Table 14 shows the results of supplementary research on the influence of temperature when measuring the sedimentation volume of the raw material for abrasives. This study is an investigation of measured values obtained by changing the measurement temperature when measuring the sedimentation volume of the raw material for abrasive produced in Example 6.

Table 14

temperature(℃) The measured value of sedimentation volume (mL) 5 61 10 53 15 52 20 51 25 51 30 51 40 50 50 48 60 38

As can be seen from Table 14, there is no significant difference in the measured value of the sedimentation volume in the range of the measurement temperature of 10 to 50°C. Therefore, the measurement of the sedimentation volume is preferably measured within this temperature range. In addition, the numerical values of the sedimentation volume shown in this embodiment are all the results measured at 25°C.

Evaluation 2: Evaluation of Apparent Specific Volume by Standing Method

In Tables 8 to 11, the numerical values of the apparent specific volumes by the standing method (indicated by FV in the tables) are shown. The static method apparent specific volume and sedimentation volume of abrasive raw materials are the same, although it changes with its manufacturing conditions, but considering the balance between grinding speed and grinding accuracy, the value of the static method apparent specific volume is preferably 1.0 ~3.0 mL/g (Examples 3~13). More preferably, it is 1.3-2.7 ml/g, and still more preferably, it is 1.5-2.5 mL/g.

Evaluation 3: Evaluation of the concentration of hexane-extracted substances

Table 9 is a table showing the relationship between the concentration of the hexane-extracted substance of the raw material for abrasive and the grinding characteristics of the abrasive. It can be seen from the table that although the hexane-extracted substance does not have a large adverse effect on the grinding characteristics of the abrasive, by increasing the hexane-extracted substance, the impact on the interface can be clearly seen when measuring the sedimentation volume of the abrasive raw material. Therefore, the concentration of the hexane extractant should be less

Evaluation 4: Evaluation by Chlorine Concentration

Table 10 is a table showing the relationship between the chlorine concentration of the raw material for the abrasive and the grinding characteristics of the abrasive. It can be seen from this table that the chlorine in the raw material affects both the polishing speed and the polishing accuracy when used as an abrasive. In order to produce a suitable abrasive, the chlorine concentration of the raw material for the abrasive is preferably at most 0.5 mass%, more preferably at most 0.3 mass%, even more preferably at most 0.1 mass%.

Evaluation 5: Evaluation I of raw material production conditions (addition time and order of addition of rare earth compound aqueous solution)

Table 2 shows the relationship between the addition time and the sedimentation volume of the abrasive raw material when adding the rare earth compound aqueous solution to the carbonic acid-based precipitant aqueous solution in the production conditions of the abrasive raw material. It can be seen from the results that with the prolongation of the addition time of the rare earth compound aqueous solution, the sedimentation volume tends to decrease, but in a wider range, the sedimentation volume is still within an appropriate range. The addition time is preferably from 5 to 1200 minutes, more preferably from 10 to 600 minutes, and still more preferably from 20 to 300 minutes, so that the sedimentation volume of the raw material falls within the above-mentioned suitable range.

In addition, as shown in Table 6, regarding the influence of the stirring speed of the carbonic acid-based precipitant solution when precipitation is generated by the reverse addition method, even if the stirring speed of the carbonic acid-based precipitant solution is set within a wide range, no sedimentation is seen. There is a large change in volume.

On the other hand, Comparative Examples 1 and 2 in Table 2 are examples in which precipitates are generated by the positive addition method, and the sedimentation volume of the abrasive raw material in these Comparative Examples is less than 30. Table 7 shows the results when precipitation was generated by changing the stirring speed of the rare earth compound aqueous solution in the positive addition method related to this result. From this result, it can be seen that when the positive addition method is adopted, by adjusting the stirring speed to an appropriate range (100 m/min or more), an abrasive raw material with a sedimentation volume of 30 mL or more can be produced.

Evaluation 6: Evaluation II of raw material production conditions (whether there is heating when the aqueous solution is mixed)

Table 3 shows the influence of heating or not and temperature on the physical properties of the raw materials for abrasives when mixing the aqueous solution of the carbonic acid-based precipitating agent and the aqueous solution of the rare earth compound. As can be seen from the table, heating during mixing of the aqueous solutions is not necessary in addition to controlling the sedimentation volume of the raw materials for abrasives. In addition, even if it is heated, if the liquid temperature exceeds 60°C, the sedimentation volume will tend to decrease. Therefore, the liquid temperature during mixing is preferably at most 60°C, particularly preferably at most 40°C.

Evaluation 7: Evaluation III of Raw Material Production Conditions (Concentration of Rare Earth Compound Aqueous Solution)

Table 3 shows the relationship between the concentration of the rare earth compound (TREO concentration) and the sedimentation volume of the raw material for abrasive when the aqueous solution of the rare earth compound is added to the carbonate-based precipitant in the conditions of the production process of the raw material for abrasive. From the results, it can be seen that although the sedimentation volume tends to increase with the increase of the concentration of the rare earth compound aqueous solution, abrasive raw materials with suitable sedimentation volumes can be obtained in a wide range. In order to obtain a raw material for abrasive with better sedimentation volume, the concentration of the rare earth compound aqueous solution is preferably from 10 to 250 g/L, more preferably from 20 to 200 g/L, expressed on the basis of TREO.

Evaluation 8: Evaluation IV of Raw Material Production Conditions (Adsorption Treatment of Rare Earth Compound Aqueous Solution)

In addition, Table 3 also shows the differences in the physical properties of the raw materials for abrasives caused by whether the residual liquid after solvent extraction is subjected to static treatment and adsorption treatment in the production process of the rare earth compound aqueous solution. From these results, it can be seen that the static treatment and the adsorption treatment have the ability to reduce the concentration of hexane-extracted substances in the raw material for abrasives. As described above, although the hexane-extracted substance does not have a great influence on the characteristics of the abrasive, it has a significant influence on the visibility of the interface in the measurement of the sedimentation volume of the raw material for the abrasive. Therefore, it is preferable to perform at least one of static treatment and adsorption treatment.

Evaluation 9: Evaluation V of raw material production conditions (cleaning effect of sediment)

Table 4 shows whether the precipitate generated by mixing the aqueous carbonate-based precipitant solution and the aqueous solution of rare earth compounds is cleaned, the number of cleaning times and the physical properties of the raw materials for abrasives. It can be seen from the table that the chlorine concentration of the raw material for abrasives can be reduced by washing, and the greater the number of washings, the greater the concentration reduction. The chlorine concentration in the raw material and the grinding properties of the abrasive are as described above. Therefore, in the manufacturing process of the raw material for abrasives, it is preferable to fully wash|clean the deposit.

Evaluation 10: Evaluation VI of Raw Material Production Conditions (Types of Carbonic Precipitating Agents)

In addition, Table 4 shows the difference due to the type of precipitant in the aqueous solution of carbonate-based precipitant mixed with the aqueous solution of rare earth compound. As can be seen from this table, no matter which carbonic acid-based precipitating agent in ammonium bicarbonate or sodium carbonate is used, the sedimentation volume of the raw material for abrasives is all within a good range. That is to say, there will not be a big difference caused by the different types of precipitants.

Evaluation 11: Evaluation VI of Raw Material Manufacturing Conditions (Types of Starting Raw Materials)

In this embodiment, two kinds of rare earth chloride (Examples 1 to 30) and Chinese cerium carbonate (Examples 31 to 35) were used as starting materials to prepare a rare earth compound solution to produce abrasive raw materials and abrasives. For comparison, cerium carbonate produced in China was directly used as a raw material (comparative example 3) to manufacture abrasives. As a result of examining the differences in these starting materials, it was found that even refined cerium carbonate such as Comparative Example 3 was inferior in sedimentation volume and grinding properties when used as an abrasive compared with each example. Therefore, even with cerium carbonate having such excellent purity, it is more effective to prepare an aqueous rare earth compound solution as in this example. On the other hand, from the comparison of Examples 1 to 30 and Examples 31 to 35, it can be seen that when the raw material is produced from the rare earth compound aqueous solution as in the Examples, the difference in the starting material does not cause the difference in characteristics.

In this embodiment, Comparative Examples 1 and 2 are different from Examples in the production conditions (the order of addition of the rare earth compound aqueous solution). As a result, the sedimentation volume of the prepared raw material for abrasives exceeded the appropriate range. For such raw materials for abrasives, suitable raw materials for abrasives can be produced by making it into an aqueous solution of rare earth compounds again (that is, even if it is a raw material for abrasives other than the standard, it can be used as a starting material and processed to produce a suitable raw material for abrasives). into a suitable abrasive material). The following example is shown as one example.

Example 45, 46

Dissolve the abrasive material prepared in Comparative Examples 1 and 2 in hydrochloric acid, filter it, dilute the filtrate with pure water, adjust the pH to 0.9 with hydrochloric acid, and prepare an aqueous rare earth compound solution. At this time, the concentration of TREO was 50g/L.

Next, the rare earth compound aqueous solution was added to the stirred carbonic acid-based precipitant aqueous solution (ammonium bicarbonate aqueous solution) at an addition time of 60 minutes. The generated precipitate was separated by filtration and washed 5 times with 100 L/time of pure water to prepare a raw material for abrasive. In addition, other conditions such as the concentration of the aqueous solution of the carbonic acid-based precipitant are the same as above.

According to the same procedure as above, the raw material for abrasive obtained in the above procedure was used as a cerium-based abrasive, and the polishing characteristics were evaluated. Table 15 shows the results.

From this result, it can be seen that even if the abrasive raw material exceeds the appropriate range, an abrasive raw material with better characteristics can be obtained by performing an appropriate treatment in an aqueous solution of a rare earth compound, and the grinding characteristics when used as an abrasive can be improved.

Claims (9)

1. A raw material for cerium-based abrasives comprising a content of cerium oxide relative to total rare earth oxides (TREO) of 30 mass % or more, a fluorine concentration of 0.5 mass % or less relative to TREO, and carbonate radicals Raw materials for cerium-based abrasives of rare earth compounds, when the raw material slurry mixed with pure water to a TREO concentration of 126 g/L is left to stand for 10 minutes, the sedimentation volume is 30 mL or more relative to 100 mL of the raw material slurry, The raw material for the cerium series abrasive is made by a manufacturing method comprising the following steps: stirring the aqueous solution of the carbonic acid-based precipitating agent, adding the aqueous solution of the rare earth compound to the aqueous solution of the above-mentioned carbonic acid-based precipitating agent to generate a precipitate, separating and washing the above-mentioned precipitate, or Stirring the rare earth compound aqueous solution at a peripheral speed of 100 m/min or more, adding an aqueous solution of a carbonate-based precipitating agent to the above rare earth compound aqueous solution to generate a precipitate, separating and washing the above precipitate, The above-mentioned carbonic acid-based precipitation agent aqueous solution is selected from at least one of alkali metal carbonate, alkali metal bicarbonate, ammonium carbonate, ammonium bicarbonate, guanidine carbonate, ammonium carbamate and urea, The content of cerium oxide in the rare earth compound aqueous solution is 30% by mass or more relative to the total rare earth oxides (TREO), and the fluorine concentration is 0.5% by mass or less relative to TREO. 2. The raw material for cerium-based abrasives as claimed in claim 1, further characterized in that, the apparent specific volume of standing method after drying at 120° C. for 12 hours is 1.0 to 3.0 mL/g, and this value is passed by JIS K 5101-1991 Measured. 3. The raw material for cerium-based abrasives according to claim 1 or 2, wherein the content of hexane-extracted substances measured when dissolved in hydrochloric acid is 700 mass ppm or less on the basis of TREO. 4. the manufacture method of raw material for cerium series abrasives as claimed in claim 1 is characterized in that, comprises following operation, stirring is selected from alkali metal carbonate, alkali metal bicarbonate, ammonium carbonate, ammonium bicarbonate, guanidine carbonate, Ammonium carbamate and at least one carbonic acid precipitant aqueous solution in urea; An aqueous solution of rare earth compounds is added to the aqueous solution of the above-mentioned carbonic acid-based precipitant to generate a precipitate. The content of cerium oxide in the aqueous solution of rare earth compounds is 30% by mass or more relative to the total rare earth oxides (TREO), and the concentration of fluorine is relatively With TREO below 0.5% by mass; The above precipitate was separated and washed. 5. The manufacture method of the raw material for cerium series abrasives according to claim 1, characterized in that, comprising the following steps, stirring the rare earth compound aqueous solution at a peripheral speed of more than 100m/min, the content of cerium oxide in the rare earth compound aqueous solution Relative to the total rare earth oxides (TREO), it is more than 30% by mass, and the fluorine concentration is less than 0.5% by mass relative to TREO; Adding an aqueous solution of at least one carbonate-based precipitant selected from alkali metal carbonates, alkali metal bicarbonates, ammonium carbonate, ammonium bicarbonate, guanidine carbonate, ammonium carbamate, and urea to the above aqueous solution of rare earth compounds to generate precipitation; The above precipitate was separated and washed. 6. the manufacture method of raw material for cerium series abrasive as claimed in claim 4 or 5 is characterized in that, rare earth compound aqueous solution makes hexane extraction by carrying out at least any one in following (a) or (b) material reduction, (a) standing the rare earth compound aqueous solution, and separating and removing the hexane extraction substance in the rare earth compound aqueous solution, (b) A treatment in which an aqueous solution of a rare earth compound is brought into contact with an oil adsorbent to adsorb and remove hexane-extracted substances. 7. The cerium-based abrasive, characterized in that it is made from the raw material for cerium-based abrasive according to any one of claims 1-3. 8. A method for producing a cerium-based abrasive, comprising using the raw material for a cerium-based abrasive according to any one of claims 1 to 3. 9. The manufacture method of cerium series abrasive, it is to use the method for producing cerium series abrasive with the raw material for cerium series abrasive according to any one of claims 1～3, it is characterized in that, comprises roasting process and before this roasting process The pulverizing step of the raw material for the abrasive material, the above-mentioned pulverizing step is to immerse the raw material for the abrasive material in an aqueous solution or water containing at least one compound selected from ammonia, ammonium carbonate, ammonium bicarbonate, guanidine carbonate, ammonium carbamate and urea, The process of heating at 60 to 100°C and pulverizing the raw materials for abrasives.

Images