GB2109356A

GB2109356A - Method of isolating alkali metal and titanium values from red slime and similar materials

Info

Publication number: GB2109356A
Application number: GB08131714A
Authority: GB
Inventors: Jerzy Grzymek; Anna Derdacka-Grzymek; Zofia Konik; Bronislaw Werynski; Wieslaw Grzymek; Zbigniew Olear; Kazimierz Bohdan Bogdanowicz
Original assignee: Akademia Gomiczo Hutnicza
Current assignee: Akademia Gomiczo Hutnicza
Priority date: 1981-10-21
Filing date: 1981-10-21
Publication date: 1983-06-02

Abstract

Alkali metal salts and titanyl sulphate are obtained by fusing red slime or a similar raw material in a reducing atmosphere with limestone and anhydrite, recovering alkali metals in form of a sublimate, separating iron, cooling the slag, leaching out aluminium oxide with alkali, and treating the residue which contains a high temperature modification of perowskite (CaO.TiO2) with sulphuric acid to obtain a titanyl sulphate solution.

Description

SPECIFICATION Method of isolating alkali metal and titanium values from red slime and similar materials The present invention provides a method for obtaining alkali metals and titanyl sulphate from red slime or a similar natural or industrial raw material or waste.

A method for the partial recovery of Na2O from slimes using Ca(OH)2 to obtain NaOH is well known. In this method, the red slime is treated in suspension with 6-12% quicklime, but the recovery of NaOH does not exceed 10-25% of theory even after 4-8 hours at a temperature of 358-373" K. The recovery of NaOH increases with increasing lime content only to a limited extent.

Another method of recovering alkali metals from red slimes consists in dissolving a mixture of a red slime, quicklime and humic acids or humic acid derivatives in water. The resulting suspension is stirred at ca 353-373" K for 1-6 hours. A large proportion of the alkali metals contained in the red slime passes into solution in form of alkali salts of humic acids and can be utilized directly, or transformed into hydroxides or carbonates.

Neither titanium nor its compounds have hittherto been recovered from red slimes.

The present invention provides conditions in which the alkali metals contained in red slime can easily sublime and titanium can be bound as a chemical compound from which titanium can be recovered in a simple way.

The process of the present invention comprises heating a mixture of the said material with lime and calcium sulphate in a reducing atmosphere so as to convert titanium values to a high temperature modification of perowskite (CaO.TiO2), to cause alkali metal values to sublime from the mixture, and to convert iron present in the mixture to metallic iron, separating the iron and cooling the residual slag, leaching the slag with alkali to remove aluminium values therefrom, and then treating the leached slag with sulphuric acid to remove titanium values therefrom in the form ot titanyl sulphate.

The red slime or other similar raw material is fused with limestone and calcium sulphate in a reducing atmosphere. The alkali-containing minerals are thereby decomposed and their oxides are reduced to the free metals. In this form they easily distil (in an 80% yield) at 1623 K, and react with 803 to form sulphates which sublime and after cooling can be retained e.g. in electrofilters.

The excess CaO formed by the decomposition of CaS04 reacts in statu nascendi with calcium titanate to form a solid solution with a defect structure of a high temperature modification of perowskite (CaO.TiO2). After separation of iron, cooling and leaching out the alumium oxide, the residue is mixed with sulphuric acid. From the titanyl sulphate solution so obtained metallic litanium or TiO2 can be obtained.

The following Example illustrates the invention. Percentages are by weight.

EXAMPLE Dried red slime of the composition SiO2 - 12.8% Fe203 - 25.6 Al203 - 24.7 TiO2 - 9.7% CaO - 8.8% S03 - 0.7% Na2O - 5.9% K2O - 0.6% MnO2 - 0.1% Other - 0.2% Loss on ignition - 10.8% is ground with limestone and anhydrite in the proportions 57% red slime, 41% limestone, and 2% anhydrite, and then fused in a reducing atmosphere. At 1623 K the alkali-containing minerals decompose. Alkali metal oxides are reduced to the free metals which distil easily at 1623 K. About 80% of the alkali metals are removed in this way. The alkali metals then react with SO3 to form sulphates which sublime and, after cooling, can be collected on an electrofilter.The excess CaO formed by decomposition of the CaSO4 reacts in statu nascendi with calcium titanate and forms a solid solution having a defect structure of a high temperature modification of perowskite CaO.TiO2.

After sublimation of the alkali metals and raising the temperature to 1823 K, the reduced iron is separated from the fused slag.

The slag is then cooled at a rate of ca 283 K/min to 973"K. On cooling the slag spontaneously disintegrates to form a powder of mean grain diameter ca 30/1m. The disintegrated slag contains a crystalline high-temperature polymorphic modification of 1 2CaO.7- Al203 and a high-temperature modification of perotvskite, CaO.TiO2.

The disintegrated slag is leached with 6% soda solution to recover aluminium oxide which pass into solution in the form of sodium meta-aluminate. The chemical composition of the residue after leaching is as follows: SiO2 - 13.8% Fe203 - 0.05% Al203 - 5.0% TiO2 - 10.2% CaO - 55.3% SO2 - 0.7% Na2O - 0.5% K20 - 0.0% Loss on ignition - 14.5% The remainder is washed out with hot dilute sulphuric acid to remove the last traces of aluminium oxide.

The residue containing 17.3% CaO.TiO2 is mixed for 30 minutes with 62% sulphuric acid in the ratio 1: 5 at ca 363"C. Titanium passes thereby into solution as titanium sulphate in a yield of 70%. After decantation and filtration the titanyl sulphate solution is concentrated. The residue, after filtration, is roasted at 623 K to recover sulphuric acid.

The powdered white remainder exhibits binding properties, colours easily and can be used as a high-quality plaster or coloured mortar.

The chemical composition of this binding material is as follows: SiO2 - 8.4% Fe2O3 - 0.0% TiO2 - 1.7% CaO - 33.5% S03 - 48.2% loss on ignition - 8.0% other - 0.2% From one part by weight of red slime, the following products are obtained: 0.177 part by weight of pig iron - Fe 0.1 98 part by weight of aluminium oxide Awl203 0.151 part by weight titanium in the form TiOSO4H2O 0.068 part by weight of TiO2 therein 0.057 part by weight alkali metals, and 0.920 part by weight binding material.

Claims

1. Process for the separation of alkali metal and titanium values from red slime and similar materials which comprises heating a mixture of the said material with lime and calcium sulphate in a reducing atmosphere so as to convert titanium values to a high temperature modification of perowskite (CaO. TiO2), to cause alkali metal values to sublime from the mixture, and to convert iron present in the mixture to metallic iron, separating the iron and cooling the residual slag, leaching the slag with alkali to remove aluminium values therefrom, and then treating the leached slag with sulphuric acid to remove titanium values therefrom in the form of titanyl sulphate.

2. Process according to claim 1 in which red slime is heated with limestone and anhydrite.

3. Process according to claim 1 or 2 in which the alkali metal values are collected in the form of sulphates.

4. Process according to claim 1 or 2 in which the aluminium values are separated in the form of sodium aluminate.

5. Process according to claim 1 or 2 in which the residue from the sulphuric acid treatment is recovered for use as a mortar or plaster.

6. Process according to claim 1 substantially as described in the Example.

7. Alkali metal sulphates, iron, sodium aluminate, and/or titanyl sulphate, when produced by the process of any of the preceding claims.