DE3226894A1 - Process for the preparation of a titanyl sulphate solution - Google Patents

Abstract

A process is described for the preparation of a hydrolysable titanyl sulphate solution by the joint decomposition of slag/ilmenite mixtures with sulphuric acid and dissolving the solidified reaction composition in an aqueous solvent, the decomposition being carried out in the presence of organic substances from the group of the polysiloxanes and/or alkanol amines and/or phosphates.

Description

Process for the preparation of a titanyl sulfate solution

The present invention relates to a method of making a hydrolyzable titanyl sulfate solution through the joint digestion of slag-ilmenite mixtures with sulfuric acid and dissolving the solidified reaction mass in an aqueous solvent.

Joint outcrops of ilmenites and titanium-containing slags, in which part of the titanium is present in reduced 3+ form as Ti numerous economic, ecological and procedural advantages.

Through the choice of a suitable ore combination, one Addition of reducing agents such as scrap iron or the use of electrochemicals Process can be dispensed with, since the Ti3 + 3+ content contained in the slag is used Reduction of the Fe content in the mixture is sufficient (EP-A 31507, EP-A 31062). the The reaction mass obtained in this way can be used directly by adding an aqueous solvent be transferred into a hydrolyzable titanyl sulfate solution that is used for production high-quality titanium dioxide pigments is suitable.

Another advantage of the mixed digestion of slag and ilmenite is there in that no sulfuric acid losses occur which occur in the reaction of Ti (III) -containing Slag with sulfuric acid through the formation of S02 or through the reaction of Ilmenite digestion solutions with scrap iron arise.

Due to the almost quantitative implementation of the reduction potential Ti (III) -containing slag with the Fe (III) -content of the ilmenite can be the total iron content of the resulting titanyl sulfate solutions are so low that there is a deposition by FeS04. 7H20 can be dispensed with.

In the case of discontinuous operation, that in practice with sulfuric acid digestion of titanium ores is widespread and consists in that the ore / sulfuric acid mixtures stirred by the introduction of air during the actual digestion reaction on the other hand, problems can arise with the viscous ones that tend to densify and consequently difficult to handle digestion cakes occur, e.g. through spontaneous Discharge of reaction material from the container. The cause of such behavior, that can seriously disrupt normal operations is not known. In addition it has been observed that the problems described do not occur predictably, what a procedural problem solution is particularly difficult.

The addition of various organic auxiliaries to sulfuric acids Outcropping of titanium ore is in itself known. So in the US PS 2,850,357 the addition of carbonaceous materials to digestions of Ti (III) -containing Described slags to reduce the Ti (III) content of the digestion solutions. Precisely this is disadvantageous insofar as the reduction potential contains more Ti (III) Slag not quantitatively for the reaction with the Fe (III) content of the ilmenite can be available.

Further organic additives are disclosed in US Pat. No. 2,066,093 and US Pat US Pat. No. 3,397,037 describes the yield, solubility of the digestion cake and the To improve the porosity of the digestion cake. But they are from the ones described above Unsuitable reasons for the digestion of slag-ilmenite mixtures.

The use of the organic additives mentioned has in addition the disadvantage that it leads to a reduction in the degree of digestion or excessive SO2 emissions leads.

The aim of the present invention is therefore to provide a simple and Specify inexpensive method with the help of which one can look at the detailed Advantages of the joint digestion of slag / ilmenite mixtures with sulfuric acid can be made usable without the difficult-to-handle digestion cakes that tend to compress develop.

Surprisingly, this is achieved when organic substances are used in the digestion Substances from the group of polysiloxanes and / or alkanolamines and / or phosphoric acid esters can be added.

The present invention therefore relates to a method of production a hydrolyzable titanyl sulfate solution through the joint digestion of Schlakke-ilmenite mixtures with sulfuric acid and dissolving the solidified reaction mass in an aqueous solvent, characterized in that the digestion takes place in the presence of organic substances the group of polysiloxanes and / or alkanolamines and / or phosphoric acid esters carried out will.

The use of polysiloxanes and / or phosphoric acid esters and / or Alkanolamines effectively improve the handleability of digestion cakes without the to produce known disadvantages. It is sufficient to use the organic substances or their mixtures before or in the initial phase of the digestion reaction in amounts of 0.05% by weight to 2.0% by weight, based on the ore used, of the slag-ilmenite mixture admit. The organic substances are preferably used before the actual digestion reaction added.

The polysiloxanes used can be chain, branched or be constructed cyclically and alkyl, aryl and / or cycloalkyl radicals and hydroxyl radicals exhibit.

Polydimethylsiloxanes are due to economic considerations particularly suitable. Phosphoric acid di- and tri-esters are used as phosphoric acid esters in question, which also have alkyl, aryl and / or cycloalkyl radicals.

Examples of the alkanolamines to be used according to the invention are Triethanolamine, tripropanolamine, diisopropanolamine, etc.

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

A particularly preferred embodiment of the method according to the invention it is, the organic substances already in the usually preceding the digestion To add grinding of the ores and ore mixtures. In addition to a particularly intensive mixing The additives turn out to be the organic additives with the good to be digested as excellent grinding aids.

The following examples illustrate that it is by the invention Procedure in a simple and inexpensive manner is possible, the advantages outlined of slag / ilmenite digestions without any disadvantages in terms of manageability To have to accept, especially with a conventional, in practice many times practiced discontinuous digestion process, consisting in the introduction of air for the mixing of ore and acid, were observed.

The method according to the invention is explained below by way of example. Unless otherwise stated, all percentages are percentages by weight.

The experiments were carried out in the apparatus shown in FIG. Numbers (1) to (17) identify the following parts: 1) glass vessel, 10 cm, cylindrical part 20 cm, conical part 10 cm long, 2) brass vessel with Heating bandage and asbestos cord wrapped in an externally insulated protective vessel, 3) immersion tube for the introduction of air, 4) rubber cover, 5) tube furnace for air heating, 6) thermocouple with controller (7) and transformer (8) 9) rotameter, 10) transmitter and Pressure recorder (11), 12) transformer for vessel heating, 13) double element for transformer and Recorder (14), 15) thermocouple for recorder (mixed temperature), 16) thermometer (Mixed temperature), 17) dropping funnel, Example 1 - 5 In the in The digestion apparatus described in more detail in FIG. 1 was 315.1 g of an H2SO4 content of 65.0% concentrated dilute acid and 400 g on a ternary raw material mixture, consisting of 80 g of ilmenite ground to a grain size of 98% <40 Å, the a TiO2 content of 60.2%, an iron content of 25.0% and an iron (III) content of 17.4%, 208 g to a grain size of 91.9% <40 ß of ground slag A, which has a TiO2 content of 86.2%, a titanium (III) content of 28.8% (calculated as TiO2 and based on slag) and an iron content of 7.7%, as well as 112 g of slag B ground to a grain size of 87.8% <40 ß, the one TiO2 content of 71.6%, a titanium (III) content of 8.7% (calculated as TiO2 and based on slag) and has an iron content of 9.3%.

Then 0.3 g of a 35% emulsion was added to the ore / acid mixture of a polydimethylsiloxane with an average molecular weight of approx. 8000 (Baysilon emulsion »from BAYER AG). 3 minutes after switching on the 750 watt heatable Air bath, which is used to compensate for heat losses due to radiation, was passing through 500 1 air / hour.

within 10 min. 442 g of oleum with an SO3 concentration of 19.7% Start of the digestion reaction added.

The temperature of the air stream introduced became the internal temperature of the vessel tracked to reduce heat losses avoid. Case in point for the temperature-time course of the digestion reaction and the time of solidification is contained in FIG. Therein la) mean the first temperature maximum, (b) that second temperature maximum, (c) the solidification point.

In this way, 5 tests were carried out, with the temperature-time course and the solidification point matched with the exception of slight deviations and that of Fig. 2 corresponded. In all 5 examples, the Digestion reaction observed.

After completion of the digestion reaction, the solidified reaction mass became in a drying cabinet for 5 hours

aged at 1800C and then by adding 800 ml of water at 700C within 4 hours while passing 100 liters of air / hour through. solved. It found an average of 94.1% of the TiO2 used is in the solution.

The average Ti (III) content of the solutions was 9.5% des dissolved TiO2.

Comparative Examples AE The comparative examples AE correspond with regard to the mode of operation in all respects the examples 1 - 5 with the exception, that no silicone oil emulsion was added. Occurred in all 5 comparative examples occurs when or shortly after reaching the 2nd temperature maximum B (cf. FIG. 2) spontaneous pressure increase - with discharge of part of the solidified reaction mass from the decomposition vessel. Collected parts of the reaction mass became Aged and dissolved according to Example 1 - 5. It was average 94.6% of the TiO2 used in solution. The average Ti (III) content was at 4.4% of the dissolved TiO2. Examples 1 - 5 in comparison to A - E illustrate that the silicone oil emulsion additive facilitates the handling of common slag / ilmenite digestions effectively improved.

Examples 6 - 9 The procedure was as in Example 1 - 5, with the difference is that instead of the silicone oil emulsion, 0.4 g of a mixture of 1 Part mono- and 1 part di-isopropanolamine of the acid / ore mixture before the start of the digestion reaction was added. A smooth, trouble-free reaction process was found in all 4 experiments observed.

After aging and the loosening procedure were average 94.5% of the TiO2 used in solution. The average Ti (III) content was 6% of the dissolved TiO2.

This means that mono- and di-isopropanolamine mixtures are also easier to handle of common slag / ilmenite outcrops.

Example 10-12 The procedure was as in Example 1-5, with the difference that instead of the silicone oil emulsion 0.4 g Tri-n-butyl phosphate were added. A disruption-free digestion reaction was found in all 3 experiments observed. After appropriate further processing, there were average 93.9% of the TiO2 used in solution. The average Ti (III) content was 2.4% of the dissolved TiO2. It follows from this that the handling is also possible with tributyl phosphate of digestion cake from slag / ilmenite mixtures can be improved.

Example 13 To show that the effectiveness of the additives does not increase a certain ore mixture is restricted, the following example has the composition the ore mix changed. 80 g of the ilmenite characterized in Example 1 were obtained with 176 g of slag A and 144 g of slag B in 320.2 g of one concentrated to 65% Submitted dilute acid, added 0.3 g of Baysilon oil emulsion O and added 428.2 g of oleum the digestion reaction started at an SO3 concentration of 24%. Unless specified, all other test conditions correspond to those of Examples 1-5.

The reaction process is trouble-free. After appropriate further processing 94.1% of the TiO2 used was in solution, with 6.9% of the dissolved TiO2 was present as Ti (III).

Comparative Example F The procedure of Example 13 was followed, with the The difference is that no silicone oil emulsion was added. About 5 minutes after exceeding the 2nd temperature maximum B (see. Fig. 2) there was a spontaneous increase in pressure in the digestion mass and a discharge of reaction material from the vessel. After further processing 93.7% of the TiO2 used was found in solution. The Ti (III) content was 5.7% of dissolved TiO2.

Examples 14-16 Another variation of the ore mixture was made; 60 g of ilmenite, 148 g of slag A and 192 g of slag B were used, which in 320.2 g dilute acid concentrated to 65% were entered.

After using 0.4 g of Baysilon oil emulsion t-2, 420.8 g of oleum were added the reaction started with an SO3 concentration of 24% and otherwise analogous to the example Procedure 1 - 5. The course of the reaction was trouble-free.

Comparative Example G The same procedure as in Examples 14-16 was followed, with the difference is that no silicone oil emulsion was added.

36 minutes after the start of the reaction, there was an increase in pressure in the decomposition device.

Example 17 Example 17 is intended to show that the inventive Method is also applicable to binary ore mixtures. 100 g of ilmenite were used and 300 g of slag A, which entered 333.4 g of dilute acid concentrated to 65% became. After adding 0.4 g of Baysilon-Olemul-R sion O with 451.1 g of oleum a S03 concentration of 22.2% started the reaction and otherwise analogous to the example Procedure 1 - 5. The course of the reaction was trouble-free. The salary of the Solution was 93.5% of the Ti02 used; 13% of the dissolved Ti02 was in the form of Ti (III).

Comparative Example H The procedure of Example 17 was followed, with the The difference is that no silicone oil emulsion was added.

36 minutes after the start of the reaction, there was a slight increase in pressure in the digestion material, so that the reaction mass was raised in the digestion vessel.

Example 18 Example 18 is intended to show that the inventive Organic additives are also effective when used in place of pre-concentrated sulfuric acid and oleum is worked with sulfuric acid and water.

400 g of the ore mixture of Examples 14-16 are dissolved in 679.3 g of sulfuric acid 96% registered. After addition of 0.6 g of tributyl phosphate the digestion reaction was started with 61.8 g of water and otherwise analogous to the others Proceed with examples.

The course of the reaction was trouble-free. In the solution, 93.6% of the TiO2 used found; 2% of the dissolved triol was in the form of Ti (III) before.

Comparative Example J The procedure of Example 18 was repeated, with the The difference is that the tributyl phosphate was not added. It came after about 60 minutes to a pressure increase in the decomposition vessel accompanied by a discharge of parts the reaction mass.

Claims (1)

Claims: 1. Process for the preparation of a hydrolyzable Titanyl sulfate solution through the joint digestion of slag-ilmenite mixtures with sulfuric acid and dissolving the solidified reaction mass in an aqueous solvent, characterized in that the digestion takes place in the presence of organic substances the group of polysiloxanes and / or alkanolamines and / or phosphoric acid esters carried out will. 2, method according to claim 1, characterized in that the organic Substances or their mixtures in amounts of 0.05 to 2 wt .-%, based on the ore used to be added to the slag-ilmenite mixture. 3. The method according to any one of claims 1 or 2, characterized in that that the organic substances react to the slag-ilmenite mixture before the digestion are mixed in. 4. The method according to any one of claims 1 to 3, characterized in that that the organic substances in the form of aqueous emulsions and / or solutions be added. 5. The method according to any one of claims 1 to 4, characterized in that that the organic substances are added during the grinding of the ores or mixtures of ores.