JPH0781168B2 - Clay Ni ore briquette method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for briquetting a clayey Ni ore, and particularly in a briquetting step for smelting Ni oxide ore or the like to produce ferronickel, It proposes a novel technique for adjusting a briquette material supplied to a briquette machine (hereinafter, referred to as a "briquette machine") by focusing on clay content and water content.

[Conventional technology]

Generally, Ni (ferronickel) used in the production of austenitic stainless steel is produced by smelting Ni silicate ore such as garnilite. This oxidized Ni
Ore is a viscous wet ore and contains a large amount of water, so it is usually smelted as follows.

That is, the method called the all-wet method is such that first, a large amount of water is added to each of the main raw material and the auxiliary raw material such as ore, carbonaceous material, and limestone, and individually wet-milled as a slurry, and then these raw materials are Mix and dehydrate the mixed material before pelletizing into pellets or the like. After that, the product was charged into, for example, a great rotary kiln, and dried, preheated, and calcined to reduce the metal content such as Ni and grow as a loupe, and then discharged as a clinker, This is a method in which ferronickel and other ferroalloys are converted from this clinker by treatment.

However, according to this method, a large amount of water is added to the main raw material and the auxiliary raw material, and the water is removed as a slurry with a drum filter or the like. Therefore, dehydration is not sufficient, and further mixing is performed in a slurry state with each raw material. Therefore, it is difficult to mix the raw materials uniformly, and it is very difficult to disperse and mix the carbonaceous materials having a large difference in specific gravity in a large amount and uniformly.

On the other hand, in order to overcome such drawbacks, the present applicant has
In Japanese Unexamined Patent Publication (Kokai) No. 62-23944, the main raw material NiO
The ore is divided into two according to the quality of dehydration, one of them, that is, the ore with poor dehydration is crushed through the dry crushing process, and the other ore, that is, the ore with good dehydration is crushed through the wet crushing process. A method of crushing to prepare a mixed raw material was proposed.

The technology according to this prior proposal will be described below.

The dry crushing step is a step of crushing the ore in a dry state, and the ore can be constituted in any manner as long as it can be normally crushed to a diameter of about 2 mm, but normally, as shown in FIG. The cyclone 2 and the back filter 3 are connected to each other. Above all, dry air is sent from the hot air stove 4 to the attritor 1. Therefore, some of the ore is usually 25
It contains about 40% water and has a diameter of about -300 mm, but it is crushed in a dry state in a grinder 1 such as a ball mill to obtain a particle size-
It is adjusted to about 2 mm and dried to a water content of about 10% or less.

On the other hand, the wet crushing step is a step of processing ore having a good dehydration property into a slurry state, and usually comprises a wet tube mill 5 and a plurality of slurry tanks 6 as shown in FIG. The filter 7 is connected. In other words, ore with good dewatering property (also usually contains 20 to 30% of water and has a particle size of about -300 mm) is added with water and crushed by the wet tube mill 5 to remove about 50% of water. A slurry containing the slurry is temporarily stocked in the slurry tank 6, and then the drum filter 7 sequentially supplies water with a moisture content of 28 to 35.
Dehydrate to about% and make cake.

Next, each raw material adjusted to a particle size of about −2 mm is mixed and kneaded in appropriate amounts in a mixing and kneading step. Moisture of each raw material at this time, the crushing strength of the briquette and the drying of the subsequent process,
10-20% from the heat energy saving of preheating, etc., preferably
15 to 20%.

That is, in the subsequent bridging process, a certain amount of water is required to increase the strength of the briquette or other braided product. On the other hand, if the amount of water is too large, the briquetting property will be impaired and preheating will be difficult. A large amount of heat energy is required for drying,
Exhaust gas during reduction firing may not be able to dry it sufficiently, and from this point the upper limit is around 20%.

[Problems to be Solved by the Invention]

Conventionally, the mixed raw materials have been qualitatively adjusted for moisture mainly from the moldability of briquettes, but when focusing on the mixing characteristics of the raw materials and the strength of briquettes, simple moisture adjustment as described above is not sufficient. I knew that.

FIG. 2 shows the relationship between the water content and crush strength of various brands of ores. As can be seen from this figure, it is clear that all raw materials have the same tendency in that the crushing strength becomes stronger as the water content becomes lower.

However, depending on the type (brand) of the raw material, it was found that there was a significant difference in the range of desirable suitable water content for achieving the desired briquette strength, and it was practically difficult to control the water content.

The object of the present invention is to propose a technique capable of overcoming the disadvantage of the prior art in that a desired briquette cannot be produced due to the inability to prepare a mixed raw material suitable for obtaining such desired briquette strength. is there.

[Means for Solving the Problems]

In view of the circumstances of the art as described above, the present invention has a stable crushing strength, and as an excellent method of formability (grouping), a dry or wet-processed clay-like Ni ore according to dehydration is used. In a method of mixing and adjusting powders in appropriate amounts to obtain a water content necessary to obtain a desired briquette strength, and mixing the mixed raw material whose water content is adjusted in this way through the briquette machine, Upon blending the mixed raw materials to be supplied, the average clay content of the entire mixed raw materials according to the blending amount of each of the ore brands to be mixed is obtained, and an appropriate water content is obtained according to the average clay content of the mixed raw materials, and the calculation thereof is performed. Add the required amount of water according to the amount of water, and then knead the mixed raw material after adding water,
We propose a briquetting method of clayey Ni ore, which is characterized by performing homogenization by curing and then briquetting.

As a specific water content adjusting method, the clay content of each ore brand is individually calculated based on the blending amount, and the weight average clay content of the entire blended mixed raw material is calculated, and the obtained total blending raw material is obtained. This is performed by calculating an appropriate moisture value for obtaining a predetermined crushing strength based on FIG. 3 described later according to the average clay content, and adding this calculated moisture as an appropriate moisture content.

By adjusting the water content in this way, it becomes possible to mix the ore with the most appropriate water content in consideration of the clay content of each ore brand, and it becomes possible to accurately control the target briquette strength.

In the above briquetting method, the water content of the mixed main raw material to be controlled increases as the clay content increases, but a preferable clay content requires 50% or more of the clay content in the state where various ores are mixed.

[Work]

Generally, the bond strength of briquette involves a chemical bond strength in the case of using a binder, and a melting bond strength in the case of performing firing or hot briquette. On the other hand, as in the present invention, in the case of molding only at the normal temperature by only the pressing force, the physicochemical bonding force, that is, the interparticle attractive force is increased by shortening the interparticle distance by the pressurization. obtain. For such a physicochemical bonding force, not only raw material particle size and compressive force but also water is an important factor. However, according to the findings of the present inventors, the ore, mainly garnilite (silicic nickel ore) In the case of such clayey Ni ore, it has been found that the clay content of the ore is particularly important. Here, the clay content of the ore is JIS A 1204 or JI.
It is a value determined based on the clay content test method for foundry sand of SZ 2601.

This is because the effect of water content on briquette strength varies greatly depending on the ore brand, as shown in Fig. 3, and the same level of water content, for example 17%, cannot always be said to be appropriate. That is, in the case of Thio in the same figure, it becomes impossible to mold, while when comparing the moldable Nakechi and Pomara, Riotuba, the latter has higher crush strength and the suitability value changes for each. Therefore, in order to obtain the final target briquette strength, it is understood that the briquette raw material must be adjusted with other parameters besides the water content or with this water content.

Therefore, the relationship between the clay content of the briquette and the suitable water content was investigated as the briquette strength for the crushing strength, and the quantification of the suitable water content was considered.

In the experiment, we selected four kinds of ores of chemical composition −2mm, which we obtained as shown in Table 1 below, such as Thio, Nakechi, Pomara, and Riotuba, and also mixed them with −2mm of carbonaceous material, limestone and dust. Then, add a predetermined amount of water to make water samples of various briquette from 15% to 23%.
After sieving with a sieve, the mixture was aged for 3 days while adding a blending operation, and then molded into a briquette of 40 mmφ × 20 mm while applying a load of 3 t. This was subjected to a crushing strength test.

The result of the crushing strength test is already shown in FIG. Although the crushing strength could be measured only up to 30 kg due to the scale, scale-over was observed on the low moisture side of the above Pomala or Riotuba ore, but the tendency for the strength of all brands to decline as the moisture content increased. In particular, low clay powder ore has low strength as a whole, and water exudation was observed during briquette molding from the side of considerably low water content (marked with a cross in the figure). It turned out to be a weak bridging.

From the above results, it was found that the existing state of water in the raw material has a great influence on the crushing strength of briquette. That is, when free water appears between the raw material particles, briquette strength remarkably decreases. It is considered that the presence of free water facilitates movement of the briquette constituent particles using water as a lubricant.

The present inventors have found that there are some types of free water that are likely to appear depending on the type of minerals and others that are difficult to appear, which are related to the clay content of the ore. That is, Fig. 3 shows the results of crushing the sample ore into -100 mesh and examining the presence of clay and free water. To increase the strength of the briquette, at least the solid line in the figure should be used. It is understood below that the raw material moisture should be suppressed. This means that, for example, when 18% is selected as the water content of the briquette, it is necessary to secure about 55% or more of the clay content of the -100 mesh standard sample of the raw ore.

For low-moisture samples (<14%) for all ores,
When the briquette was formed, it was confirmed that the raw material was caught in the mold. Moreover, if the clay content of the ore becomes too large, on the contrary, the raw material tends to settle in the mold, so the upper limit is considered to be about 80%.

As described above, the relationship between the clay content and the water content for obtaining the target briquette strength is as shown in FIG. 3, and if the appropriate water content of the raw material is determined within the range surrounded by the solid line in this figure, Allows desired bridging.

Next, in the present invention, the mixed raw materials supplied to the briquette machine need to be kneaded and cured for homogenization. Because, in the case of the present invention, since the raw material treatment is carried out in a semi-dry method in which the wet treatment and the dry treatment are combined depending on the dehydration property of the ore, the water content of the mixed raw material to be mixed is significantly different, This is because uniform mixing is difficult in a short time.

In order to solve the problem, in the present invention, the kneading and curing is sufficiently performed by taking a long mixing time or increasing the load of the rod mill to homogenize the mixed raw material.

That is, in the mixing and kneading step, as described above, a large amount of carbonaceous material is blended in addition to the main raw materials, and the water content is adjusted as described above, and on top of that, these mixed raw materials must be uniformly dispersed. There is. That is, after kneading the raw materials, the diameter 20-30
The product is formed into pillow type or almond type briquettes having a size of about mm. However, if the moisture and the interior raw materials are nonuniformly present at this time, the briquette strength is lowered. Therefore, the kneading needs to be further kneaded as compared with the conventional example. From this point, in the method of the present invention, as shown in FIG. 1, a mixer 10 such as a pug mill and a kneader 11 such as a rod mill are connected in series.
In this way, after mixing with a mixer 10 such as a pug mill in advance,
When slightly kneading at the same time with a kneading machine 11 such as a rod mill, the particles in each raw material that has already been crushed are further sized by the crushing by the kneading machine 11 such as a rod mill, and uniformly stirred and kneaded to obtain a water content. And the carbonaceous material is uniformly dispersed, and the forming property is enhanced.

The kneaded material that has been uniformly kneaded is temporarily in the raw material yard.
It will be stocked in 12 and sent to the next manufacturing process as required.

〔Example〕

5 to 15 wt% of carbonaceous materials, 6 to 10 wt% of limestone powder as auxiliary raw materials, and 10 to 20 wt% of returned dust to the main raw materials obtained by mixing the ores shown in Table 1 in the mixing ratios shown in Table 2. The briquette raw material was adjusted by adding%.

The briquette machine (capacity 27t / Hr) is used for this briquette material, gate opening is 50-150mm, roll clearance is 1-4m.
m, roll pressure 80 to 150 Kg / cm ² , roll rotation speed 10 to 15
It was assembled at rpm. The results are shown in Table 3.

As can be seen from these results, briquettes having satisfactory strength were obtained with high yield.

〔The invention's effect〕

As described above, according to the present invention, the briquette strength can always be controlled to a certain level or more, the molding yield can be improved, and in particular, molding failure and pulverization can be significantly reduced. Is stable.

[Brief description of drawings]

FIG. 1 is a flow sheet for carrying out the method of the present invention, FIG. 2 is a graph showing the relationship between water content of briquette raw material and crush strength, and FIG. 3 is water content of briquette. It is a graph which shows the relationship with clay powder and briquette strength. 1 ... Grinding machine, 2 ... Cyclone, 3 ... Bag filter, 4 ... Hot air oven, 5 ... Wet tube mill, 6 ... Slurry tank, 7 ... Drum filter, 8 ... Rod mill, 3 ', 9 …… storage tank, 10 …… mixing machine, 11 …… kneading machine,
12 …… raw material yard, 13 …… grade, 13 ′ …… bunting machine,
14 …… Exhaust chute, 15 …… Rotary kiln, 16 ……
Burner.

Claims (1)

[Claims] 1. A dry or wet treated clayey Ni ore powder is mixed and adjusted in an appropriate amount to obtain a water content required to obtain a desired briquette strength, and the water content is adjusted in this manner. In the method for forming a mixed raw material through a briquetting machine, in the mixing of the mixed raw material to be supplied to the briquetting machine, the average clay content of the entire mixed raw material according to the blending amount of each of the ore brands to be mixed is calculated. Obtain the appropriate water content according to the average clay content of this mixed raw material, add the required amount of water according to the calculated water content, and then homogenize by kneading and curing the mixed raw material for which water addition has been completed. A method for briquetting a clayey Ni ore, which comprises forming and then briquetting.