NO832454L - PROCEDURE FOR THE PREPARATION OF A HYDROLYSIBLE TITANYL SULPHATE SOLUTION - Google Patents

Description

The invention relates to a method for producing a hydrolyzable titanyl sulfate solution of mixed

ings of pre-ground ilmenite and titanium(III)-containing raw materials, especially titanium(III)-containing slag, digestion of raw material mixtures with sulfuric acid and dissolution of the solid

made reaction masses in an aqueous solvent.

When digesting ore for the production of valuable components contained therein, it involves heterogeneous reactions where solid substances react with liquid or melt-liquid components.

For heterogeneous reactions, it generally applies that the reaction rate or substance turnover per unit of time is essentially determined by the size of the surface of the solid body. For a high reaction rate or as complete a substance turnover as possible, it is advantageous to have provided a solid body with the largest possible surface area. The surface area of a given quantity of solids is largely determined by the size of the particles. The surface area available for a heterogeneous reaction is greater the smaller the individual particles are.

An increase in the surface of solid bodies is usually achieved by template processes. Before digestion, the solids to be digested are usually ground in milling aggregates such as drum-ball mills, ball-swing mills, pendulum mills or roller mills that are equipped with suitable screening devices to a specific fineness. It is known that the energy efficiency of such dry paints is very unfavorable and there has previously been no shortage of efforts to improve this situation.

Despite all improvement measures, however, the grinding of titanium ores is still very inefficient from the point of view of energy utilization, and there remains a desire for stronger optimization.

According to US patent 2,437,164, grinding of titanium ore, especially ilmenite, can preferably be carried out in the presence of naphthenic acids.

Due to economic, ecological and also process engineering advantages, an increasing number of binary or even tertiary raw material mixtures are used for the production of hydrolyzable titanyl sulfate solutions. Alongside ilmenite, these consist to a large extent of titanium-containing slag which, in contrast to ilmenites, has a more or less high content of trivalent titanium.

However, the presence of naphthenic acids with a sulphurous acid content in titanium(III)-containing raw material mixtures leads to considerable disadvantages during the course of the process. A strong foam formation thereby requires the exit of reaction material from the digestion vessel, moreover, a strong SC^ development takes place during the digestion reaction. Finally, the titanium(III) content of the slag is practically completely broken down during digestion, so that titanyl sulphate solutions are formed which are poorly suited for the hydrolysis. The breakdown of trivalent titanium with the help of various carbon-containing compounds such as naphthenic acid is also discussed in US patent 2 850 357.

It was therefore an aim of the present invention

to provide a method for an improved ore grinding which does not have the above-mentioned disadvantages, and in particular is universally applicable to titanium-(III)-containing slag.

Surprisingly, it was found that the addition of alkanolamines and/or polysiloxanes during the dry painting of titanium slag leads to a clear improvement of the paint without producing other disadvantages such as, for example, a high SO2 emission, decomposition of the titanium (III) content, foaming , or unsatisfied turnout dividends.

The object of the invention is thus a method for producing a hydrolyzable titanyl sulfate solution from mixtures of previously ground ilmenite and titanium(III)-containing raw materials, especially titanium(III)-containing slag, digestion of raw material mixtures with sulfuric acid and dissolution of the solid

made reaction masses in an aqueous solvent as the titanium(III)-containing raw materials are ground in the presence of organic auxiliary substances from the group of alkanolamines and/or polysiloxanes.

The auxiliaries or agents are added to the slag to be milled in amounts of from 0.02 to 0.5% by weight, preferably 0.005 to 0.15% by weight, even small amounts giving a clear economic advantage. The addition can take place before the actual grinding of the slag, but also with the help of suitable introduction devices in the mill during the grinding process. A method is preferred where the aid is added to the slag before the previous drying before the paint. It is beneficial, but is not a limitation of the inventive idea, to add auxiliaries in the form of ordinary solutions and/or emulsions, as this promotes better distribution of the auxiliaries over the overall surface of the paint material. Addition of the aid can be done in mixing drums but also, for example, with atomizing devices. In principle, all methods are suitable which ensure an even distribution of the aid over the total volume of the goods to be painted.

Particularly good results are obtained when the alkanolamine is

a monoisopropanolamine and/or a diisopropanolamine, and/or triisopropanolamine.

The polysiloxanes used can have a chain-shaped, branched or cyclic structure, and have alkyl, aryl and/or cycloalkyl residues and/or hydroxyl residues. Due to economic considerations, polydimethylsiloxanes are particularly suitable.

In order to achieve artificial distribution of the organic auxiliary according to the invention, it is advantageous to add these in the form of aqueous emulsions and/or solutions.

Methods according to the invention can in principle be applied to the most diverse designs of dry milling aggregates such as ball drum, ball swing/pendulum or roll-roll mills. In any case, a clear improvement of the paint is achieved, which either manifests itself with the same applied paint performance in an increased fineness of the painted goods or by striving for the same fineness leads to a reduction in the painting duration or, expressed differently, to an increase in production performance of the grinding material using the mill. This results in considerable energy savings in terms of the grinding energy to be used.

In the case of ordinary, discontinuous sulfuric acid dissolution

of ore mixtures of the type mentioned, difficulties have frequently occurred which are due to the reaction temperature passing 2 or more maxima. It requires that the reaction mixture does not solidify uniformly or only after a long time delay after crossing the reaction temperature maximum. These effects can affect the course, handling, monitoring and management

of the operational support reaction.

It was found that the grain sizes of the ore used when carrying out the joint sulfuric acid digestion of ilmenite and titanium-containing slags are of decisive importance.

The mentioned difficulties do not arise when the ilmenite raw materials used for the hydrolysis are relatively coarser in terms of their average particle size than the titanium(III)-containing raw materials used.

This recognition stands in contrast to the general opinion according to which the ilmenites and titanium-containing slags used in sulfuric acid digestion must be as fine as possible.

divided in order to achieve a satisfactory absorption ratio (cf. e.g. Winnacker-Kuchler, Chemische Technologie, 2 editions, volume 2, page 512).

Particularly good results are achieved when, when using ilmenite raw materials with an average particle size of 0-90% less than 40 y, titanium(III)-containing raw materials are used with an average particle size of 91-100% less than 40 y, and that when using ilmenite raw materials with average particle size of 0-60% less than 40 y, titanium(III)-containing raw materials with an average particle size of 65-100% less than 4 0 y are used.

Grinding of the raw material takes place in the above-mentioned grinding aggregates, which are equipped with suitable safety devices to achieve a targeted setting of the grain size distribution of the grinding material. The grain sizes can also be produced using pendulum mills or roller mills. Optionally, the setting of a specific particle size of the ores prescribed for the sulfuric acid digestion can also take place with the help of screening devices,

like for example. swing sights or air jet sights.

The additive according to the invention enables the grain size to be used to be achieved economically

(see fig. 5).

In addition to achieving a good digestion result, the ore mixtures with the defined grain sizes are distinguished by the fact that the used ore components of the raw material mixture, after starting the digestion reaction, at the same time reach the maximum reaction temperature, and the mixture solidifies uniformly upon reaching this temperature. Such ore mixtures allow

with sulfuric acid can also be absorbed without problems in discontinuous charge operation.

In the following, the method according to the invention is explained by way of example. If nothing else is stated, all percentages are given in % by weight.

The experiments were carried out in the one in fig. 1 showed apparatus. Here the numbers 1 to 17 indicate the following parts: 1) Shard of glass, diameter 10 cm, cylindrical part 20 cm, conical part 10 cm long. 2) Brass vessel wrapped with heat bandage and asbestos cord located in an externally insulated protective vessel,

3) Dip tube for introducing air,

4) Rubber lid,

5) Tube furnace for air heating,

6) Thermocouple with regulator (7) and transformer (8),

9) Rotameter,

10) Transmitter and printer (11),

12) Transformer for vessel heating,

13) Double relay for transformer and printer (14),

15) Thermocouple for printer (mixing temperature),

16) Thermometer (mixture temperature),

17) Drip funnel.

Example 1-16

The titanium raw materials specified in Table 1 are brought over a sieve to a uniform grain size < 1 mm, sprayed with the auxiliaries listed in Table 1, possibly dried at 150°C, and filled in portions of 300 g into steel cylindrical measuring cups (volume 1000 ml), 1800 g steel balls of 15 mm diameter are added,

and the measuring cups are turned on a rolling table for 8 hours. After completion of the painting procedure, per sieve analysis determined the percentage amount of different fractions and thus determined

the particle size distribution. The results are shown in table 1, and show that the addition of the auxiliaries according to the invention leads to an increased fineness of the grinding material.

Example 17-28

The titanium(III)-containing slags B specified in Table 2 are brought over a sieve of a uniform grain size

<. 1 mm, is sprayed with alternating amounts of a 60% aqueous solution of a mixture of 1 part by weight of monoisopropanolamine and 1 part by weight of diisopropanolamine and dried at 150°C.

The slag prepared in this way was filled in quantities of 300 g in steel measuring cups (volume 1000 ml) to which 1800 g of steel balls of diameter 15 mm were added, and on a vibrating device ("vibrator" company Siebtechnik, Muhlheim-Speldorf) subjected to a swing-painting. The results of these series of experiments show that at the same grinding time, the addition of the aid causes an increase in the fineness, resp. of the fineness that is achieved after 3 hours of grinding time without an aid by using the grinding aid in suitable quantities, is already present at 2 hours of grinding time. That is to say, a reduction of the painting time of around 33% is achieved.

Example 29-33

A titanium(III)-containing slag of the following composition was used for grinding experiments:

86.2% Ti02, 28.8% Ti (III) calculated as Ti02

a total of 7.7% Fe.

The sieve analysis of the starting material gave the following results: 85.3% 40 ym, 12.5%-90 ym, 2.2% 90 ym.

The thus characterized slag was ground in 2 rows without resp. with the addition of 0.1% of a 1:1 mixture of mono- and diisopropanolamine at different times corresponding to Examples 17-28 in a ball mill. The results are shown graphically on

fig. 2. They show that with grinding aids according to the invention, a fineness of 100% is achieved 40 y after 2 hours (A), while without the addition of aids, even after 4 hours' residence time in the mill, no adequate fineness was yet achieved (B).

Examples 34-39

Equal quantities of a slag B from examples 17-28 were reacted in a suitable digestion apparatus with an 88% sulfuric acid by diluting a 96% acid with water according to known methods, and during the digestion reactions emitted S02 quantity determined analytically. Experiments 34 and 35 serve as reference experiments and were run without auxiliary additive. Experiments 36 and 37 were carried out with the addition of 0.1% (referred to ore) and aid according to the invention from examples 17-28. Experiments 38 and 39 were carried out with the addition of 0.1% (referred to ore) naphthenic acid corresponding to US patent 2,437,164. Table 1 lists the results of this series of experiments. They show that the addition of naphthenic acid leads to an approximately 100% increase in the SO2 emission, and undesirable strong foaming occurs. In contrast, examples 36 and 37 relate to aids according to the invention with respect to SG^ emission and foam formation as reference examples 34 and 35.

Example 4 0-43

Equal amounts of a slag of Examples 29-33 were

in the apparatus according to examples 34 - 39 for digestion brought into reaction with an 88% sulfuric acid in the dilution of oleum

(25% free SO3) with a 65% sulfuric acid and the amount of SO2 emitted during the digestion reaction determined analytically. Experiments with 40 and 41 serve as reference experiments and were run without the addition of auxiliaries. Experiments 42 and 43 were carried out with the addition of 0.075% of a polydimethylsiloxane in the form of an aqueous emulsion (commercial product: "Bayer-Silikonolemulsion H", average molecular weight 8000).

Table 5 shows the results of this trial series. They show that the addition of polydimethylsiloxane does not lead to any deviation from the ratio of the reference examples.

Example 44-45

A slag from examples 29-33 is brought in here

suitable apparatus for reaction with an 88% sulfuric acid by diluting oleum (25% free SO3) with a 65% sulfuric acid. Trial 44 was run adding 0.1% mono/diisopropanolamine (1:1) trial 45 with 0.1% naphthenic acid. After preparation, the reaction mass aged for 5 hours at 180°C was dissolved in water, and the dissolved part of the TiO 2 used as well as the content of the solution of trivalent titanium determined.

The results are listed in table 6, and show that when using naphthenic acid, SG^ emission is around a factor of 5-6 higher than when using aids according to the invention, that a very strong foam formation is observed with naphthenic acid and of titanium(III) - the content is almost completely broken down with naphthenic acid.

Example 46

In the one in fig. 1 connection device mentioned in more detail

in turn, 318.6 g of a concentrated sulfuric acid with an H2SO^ content of 65.0% were filled, and 400 g of a ternary raw material mixture consisting of 80 g was introduced to a grain size of 88%

< 40 V ground ilmenite, having a TiO^ content of 60.0%, an iron content of 24.7%, and an iron(III) content of 17.4%, 160 g to a grain size of 85% K 40 y ground slag A, which has a TiO2 content of 85.3%, a titanium (III) content of 28.8% (calculated as TiO2 and referred to slag), and an iron content of

7.7%, as well as 160 g to a grain size of 77.4% <40 y ground slag B, which has a Ti02 content of 71.6%, a titanium(III) content of 9.2%, calculated as Ti02 and referred to slag (and an iron content of 9.9%). 3 minutes after switching on at the 750 Watt heatable air bath which serves to compensate for heat loss by radiation, 426.0 g of oleum with a SO^ concentration of 21 .1% to start the digestion reaction. The temperature of the introduced air flow was followed by the internal vessel temperature to avoid heat loss. The temperature-time course of the digestion reaction is shown in fig. 3. One sees the formation of another distinct maximum of the reaction temperature at approx. 32 minutes after crossing the first maximum. The initially fixed reaction mass at point c became liquid again, and when point e was reached, under a spontaneous strong increase in pressure in the reaction mass, it finally solidified. At point c, part of the digestion mass was withdrawn from the reaction vessel.

Those in the vat remaining in good standing were aged

in a drying cabinet for 5 hours at 180°C and then dissolved by adding 800 ml of water at 70°C during 4 hours while passing through 100 liters of air/hour. There was 95.0% of the used TiO 2 in the solution. The solution's average Ti (III) content was 2.2% of the dissolved TiO 2 .

The example shows that the digestion reaction when using finely divided ilmenite (expressed as a percentage <40<y>) together with coarsely divided slag proceeded undesirably with the formation of two temporally far apart maxima of reaction temperature a large delay in the duration until finally fixed - creation of the reaction mass and an unwanted pressure rise in the support vessel.

Example 4 7

The trial execution corresponded in all respects to it

from example 46 with the difference that 100% of the ilmenite used has a grain size between 75 y and 90 y. Fig 4 shows the temporal course of the temperature. In contrast to example 46, no other temperature maximum occurred. The attempt to

run without spontaneous development in the digester after corresponding separation and dissolution of the reaction mass in water found 94.8% of the used TiO 2 in solution. The average Ti(III) content of the solution was determined to be 7.2%

of dissolved Ti02.

The example shows that the use of relatively more coarsely divided ilmenite together with slag according to the invention enables a problem-free digestion ratio in discontinuous operation.

Example 48

Test execution corresponded in all respects to this for examples 46 and 47 with the difference that the grain size of the ilmenite used was 100% in the range between 90 y and 125 y. The course of the reaction corresponded to this, for example 47. There was 94.2% of the used Ti02 in solution at a Ti (III) content of 6.8% of the dissolved Ti02>According to this, further coarsening of the used ilmenite according to the invention achieved a problem-free attendance ratio.

Example 4 9

In the apparatus from example 46, 315.5 g were filled

of a concentrated sulfuric acid with an H2SO^ content of 65.0%

and introduced 400 g of a ternary raw material mixture consisting of 66.8 g to a grain size of 87.6% ^ 40 y obtained ilmenite having a Ti02 content of 59.6%, an iron content of 24.4%, and an iron (III) content of 17.2% and each time introduced 166.6 g of the two slags from example 46.

It was further proceeded similarly to example 4 6

and the reaction started with 429.3 g of oleum of an SO2 concentration of 21.8%. The temperature-time course corresponded approximately to that in fig. 3. Here too, when another temperature maximum was reached, a spontaneous increase in pressure occurred in the digestion vessel and the majority of the digestion mixture was taken out of the container. Collected parts of the reaction mass were aged corresponding to example 46 and dissolved. There was 93.2% of the TiO 2 solution used. The average Ti(III) content was 6.1% of the dissolved TiO2.

Example 4 9 serves as a comparison example for the following experiments, and shows as example 46 that when using finely divided ilmenite together with relatively coarsely divided slag, an unfavorable course of reaction is achieved.

Example 50

The procedure was as in example 4 9 with the difference that the ilmenite used was characterized by the following grain size distribution: 11% < 40 y, 10% 40-75 y, 7.8% 75-90 y, 16.3% 90-125 y , 55.1% 125-150 y. It was consequently relatively coarser than the slag used. The temperature time course corresponds approximately to that in fig. 4, i.e. only a distinct temperature maximum occurred. There was 92.2% of the used Ti02i solution. The Ti(III) content of the solution was 8.2% of dissolved TiO 2 .

Example 50 again shows that, according to the invention, the use of relatively coarsely divided ilmenite together with finely divided slag enables a problem-free digestion ratio.

Example 51

The procedure was similar to example 4 9 with the difference that the used slag A was ground in a ball mill to 100% < 40 y, and the used slag B likewise to 100%

< 40 y.

The ilmenite used was consequently—with 87.6% ^40 y—relatively more coarsely divided than the slags used.

A temperature-time course corresponding to fig. 5, i.e. compared to example 4 9, fig. 3, the second temperature maximum was only hinted at, and "there was no spontaneous pressure increase in the reaction vessel.

After corresponding further processing, 96.7% of the used TiC>2 was found in the solution. The titanium (III) content was 7.5% of dissolved TiC^.

Example 51 shows that it is possible to obtain problem-free digestion conditions that are relatively finely divided ilmenite, as long as according to the invention it is ensured that the slags used are relatively more finely divided than the ilmenite, or conversely, the ilmenite used is considered relatively coarser than the slags used.

Example 52

a) A titanium slag of the following composition, 71.6% Ti02 (of which 9.2% as Ti(III)), 7.7% Fe is milled in a continuous

ball mill with pneumatic outlet. Before entering the mill, 0.01% of a mixture of 1 part by weight of monoisopropanolamine and 1 part by weight of diisopropanolamine is added to the raw ore. The milled ore separated in a zyklon has a fineness of 89% less than 40 ym. The production output of the mill determined to be 9.01 to/h. b) One to example 52 of corresponding titanium slag was subjected to a painting under the same conditions with the difference that the

no aid was added to the raw ore before the paint. The separated milled ore has a fineness of 7.8% less than 40 ym. The mill's production output was determined at 7.83 to/h. It follows that the addition of 0.01% mono-/diisopropanolamine equal to better grinding fineness has caused an increase in production performance of around 15%.

It is clear that even by adding the smallest amounts, a large improvement in production performance is achieved.

Claims (8)

1. Process for producing a hydrolyzable titanyl sulfate solution from mixtures of pre-ground ilmenite and titanium(III)-containing raw materials, especially titanium (III)-containing slag, digestion of the raw material mixture with sulfuric acid and the dissolution of the fixed reaction mass in an aqueous solvent , characterized in that the titanium(III)-containing raw materials are ground in the presence of organic auxiliary substances from the group of alkanolamines and/or polysiloxanes. 2. Process according to claim 1, characterized in that the alkanolamine is a monoisopropanolamine and/or a diisopropanolamine and/or a triisopropanolamine. 3. Method according to claim 1 or 2, characterized in that the polysiloxane is a long-chain and/or branched alkyl-, acrylic-, cycloalkyl- and/or hydroxyl-substituted polysiloxane. 4. Method according to claim 3, characterized in that the polysiloxane is a polydimethylsiloxane. 5. Method according to one of claims 1 to 4, characterized in that the organic aids are used in the form of aqueous solutions and/or emulsions. 6. The method according to one of claims 1 to 5, characterized in that the organic aids are used in amounts from 0.002 to 0.5% by weight, preferably 0.005 to 0.15% by weight, referred to the mixture used. 7. Method according to one of claims 1 to 6, characterized in that the ilmenite raw materials used for digestion are relatively coarser with regard to their average particle size than the titanium(III)-containing raw materials used. 8. The method according to claim 7, characterized in that when using ilmenite raw materials with an average particle size of 0-90% smaller than 40 y, titanium(III)-containing raw materials are used with an average particle size of 91-100% smaller than 40 y, and that when using ilmenite raw materials with an average particle size of 0 - 60 less than 40 y. titanium(III)-containing raw materials with an average particle size of 65 - 100% less than 40 y are used.