RU2317344C1 - Method of removal of chlorine and fluorine from dust-like zinc-containing materials - Google Patents

Abstract

FIELD: non-ferrous metallurgy; removal of chlorine and fluorine from dust-like zinc-containing materials of lead-zinc processes, for example from Waelz sublimates or slag sublimates.

SUBSTANCE: proposed method includes calcination of materials for obtaining chlorine- and fluorine-containing sublimates followed by leaching-out which is conducted in sulfuric acid solution at separation of solid from solution. Then, solution is cleaned from chlorine step by step by sedimentation with the aid of univalent copper and from fluorine by sedimentation with the aid of lime, thus obtaining fluorine-containing lime cake which is dried to moisture content of 20-30% and is subjected to Waelz process treatment at extraction of zinc into Waelz oxide and conversion of fluorine and calcium into waste clinker.

EFFECT: possibility of utilization and removal of fluorine from zinc production process with waste or copper-containing clinker.

1 dwg, 1 tbl, 1 ex

Description

The invention relates to non-ferrous metallurgy and can be used to remove chlorine and fluorine from pulverized materials of lead-zinc production, for example, from Welsh sublimates or slag sublimates.

A known method of removing chlorine and fluorine from dusty zinc-containing materials, including their calcination (oxidative calcination) at a temperature of 650-700 ° C and the processing of secondary sublimates (see book Abdeev MA, Kolesnikov AV, Ushakov N.N. Weltzing of zinc-lead-containing materials. M.: Metallurgy. - 1985. - P.94). For the purification of zinc sulfate solutions obtained after processing various zinc-containing materials, methods are known that include the deposition of chlorine in the form of an insoluble precipitate of CuCl (Japanese application No. 60-228628, publ. 13.11.85 according to CL 22/19, RZH 1986-12G257P) and purification of fluorine solutions using lime, in the form of CaO and Ca (OH) ₂ or CaCO ₃ (Japanese application No. 60-200922, publ. 11.10.85 according to CL 22/19, RZHM 1986-12G258P and Japanese application No. 60-228627, publ. 11/13/85 according to class C22B 3/00, 19/26).

The disadvantage of these methods is in some cases the lack of acceptable technical solutions for the disposal of secondary sublimates, in other cases problems are solved separately or for cleaning solutions from chlorine or for cleaning solutions from fluorine.

The closest in technical essence and the achieved result is a method of removing chlorine and fluorine from dusty zinc-containing materials, including calcining welts sublimates or slag sublimates, trapping secondary sublimates and conducting their soda-water washing at the recovery stage in the 2nd stage, and at the 1st stage maintain the temperature of the washing solution 70-90 ° C and a pH of 8.5-9.0, and at the 2nd stage maintain the concentration of soda in the washing solution 30-55 g / l (see ed. certificate No. 1135786 USSR, publ. Bull. - 1985. - No. 3 according to CL C22B 7/02).

The disadvantage of this method is the problem with the disposal of halogens obtained after the removal of zinc-containing dusty materials, solutions and pulps containing simultaneously chlorine, fluorine, zinc and other non-ferrous metals, sodium and carbonates, as well as the low output of fluorine from secondary sublimates.

The technical result of this invention is the disposal and withdrawal from zinc production of fluorine with dump clinker. This result is achieved by the fact that in the method of removing chlorine and fluorine from dusty zinc-containing materials, including calcining materials to produce sublimates containing chlorine and fluorine, and their leaching, leaching is carried out in a solution of sulfuric acid to separate the solid from the solution, then the solution is gradually cleaned from chlorine by precipitating it with monovalent copper and from fluorine by precipitating it with lime to obtain fluorine-containing lime cake, it is dried to a moisture content of 20-30% and subjected to Waelz extraction of zinc and in Waelz oxide and a fluoride transfer and calcium depleted clinker.

The method is as follows (see drawing)

Dusty zinc-containing material (Waelz oxide) composition,%: zinc 60-67; lead 3-10; iron 1-5; chlorine 0.15-0.55; fluorine 0.02-0.15 is calcined at a temperature of 650-750 ° C to produce secondary sublimates with a yield of Waelz oxide of 3-5% and composition,%: zinc 40-50; lead 3-10; chlorine 3.4-12; fluorine 0.42-3.2. Secondary sublimates are dissolved in spent electrolyte, composition, g / l: zinc 40-50 and sulfuric acid 160-185, obtaining an acidic (15-25 g / l N ₂ SO ₄ ) solution of zinc sulfate, composition, g / l: zinc 130 -140; chlorine 11.4 -38.1, fluorine 1.3-9.6 and lead cake, which is filtered off and used as a commercial product. The required amount of copper cake containing up to 60% metallic copper and a solution of copper sulfate are introduced into a chlorine-fluorine-containing solution. In this case, the chlorine content in the solution decreases to 150-300 mg / L. Next, the copper-chlorine cake is separated from the solution by filtration on a filter press and used as a commercial product. Lime-fluff (pulverized lime) is introduced into a solution containing fluorine, neutralizing it with an acidity of 15-25 g / l to a pH of 4-6.5. In this case, 95-98% fluorine is removed from the solution and the final fluorine content in the solution is 100-200 mg / l. Fluorine-containing lime cake, composition,%: zinc 10-15, fluorine 3-6, calcium 25-40 are filtered off and, if necessary, dried to a moisture content of 20-30% and welded in a mixture with coke breeze at maximum temperatures of 1150-1200 ° C. In this case, zinc and other volatile metals are extracted into Waelz oxide, and fluorine and calcium are transferred to dump clinker. The proposed method is tested in laboratory conditions.

Tests have shown that the removal of chlorine and fluorine from dusty zinc-containing materials by calcining materials, leaching of secondary chlorine and fluorine-containing sublimates in sulfuric acid solutions with separation of solid and subsequent step-by-step purification from chlorine by precipitation with monovalent copper and fluorine by lime and for producing fluorine-containing cake with a moisture content of 20-30% and its further Waelz processing will allow to utilize and remove from zinc production chlorine with commercial copper-chlorine cake and fluorine with dump or copper clinker.

The limits of humidity change of fluorine-containing lime cake directed to welting are associated with obtaining maximum results of fluorine transfer to clinker. So, at a humidity of less than 20%, the transition of fluorine to clinker decreases due to an increase in mechanical dust removal and fluorine entering the Waelz oxide. At a humidity of more than 30%, the fluorine transition to clinker also decreases due to the hydrolysis in the Waelz furnace of calcium fluoride (CaF ₂ + 2H ₂ O = Ca (OH) ₂ + 2HF) and partial distillation of fluorine in the form of HF and fluorine again in Waelz oxide.

Example.

The verification of the method was carried out as follows.

Waelz oxide composition,%: zinc 62.5; lead 7.5; chlorine 0.35; fluorine 0.035 was calcined at a temperature of 750 ° C to obtain secondary sublimates of the composition,%: zinc 46.9; lead 5.84; chlorine 4.6; fluorine 0.52. Secondary sublimates were dissolved in the spent electrolyte, composition, g / l: zinc 42 and sulfuric acid 181, obtaining an acidic (24 g / l H ₂ SO ₄ ) solution of zinc sulfate, composition, g / l: zinc 138; chlorine 15.4; fluorine 1.7; and lead cake. The recovery of fluorine into the solution during the sulfuric acid dissolution of the secondary sublimates was 95%. 5.6 g of copper in copper cake per 1 g of chlorine in solution and 0.7 g of copper in copper sulfate solution per 1 g of chlorine in solution were introduced into a chlorine-fluorine-containing solution. The process was carried out at 50 ° C for 1 hour and the chlorine content in the solution decreased to 220 mg / L. Next, the pulp of copper-chlorine cake was filtered on a filter press, while obtaining copper-chlorine cake with a copper content of 50.3% and chlorine of 9.0%, which can be used as a commercial product for copper production. After copper-chlorine purification containing fluorine, fluffed lime (pulverized lime) was introduced into the filtrate, neutralizing it with an acidity of 24 g / l to a pH of 4-6.5 at a temperature of 60 ° C for 3 hours. CaO consumption 20 g / l. In this case, 94% fluorine was removed from the solution and the final fluorine content in the solution was 110 mg / L. Fluorine-containing lime cake, composition,%: zinc 14.5, fluorine 4.1, calcium 35.2 was filtered off and dried to a moisture content of 20-30% and was welded in a mixture with coke breeze at maximum temperatures of 1170 ° C for 2.5 hours . At the same time, zinc and other volatile metals were extracted into Waelz oxide, and fluorine and calcium (95%) were transferred to dump clinker.

The known method was checked in accordance with the description of the prototype, in which the removal of chlorine and fluorine from dusty zinc-containing materials was carried out at the stage of collecting secondary sublimates in the 2nd stage. At the first stage, the temperature of the solution was maintained at 80 ° C and pH 8.7, and at the second stage, the concentration of soda in the washing solution was maintained at 50 g / L. Solutions after the 1st and 2nd stages were filtered. The extraction in the solution of chlorine was 85%, and fluorine 45%. In zinc production, such a solution, as a rule, is sent to wastewater treatment plants, polluting halogens with treated effluents discharged into water bodies.

The table shows comparative verification data of the known and proposed methods for the removal of chlorine and fluorine from dusty zinc-containing materials. As can be seen from the data obtained, the use of the proposed method for the removal of chlorine and fluorine from dusty zinc-containing materials can increase the removal of fluorine by 84.8 (0.95 × 0.94 × 0.95 ¹ ) -45 = 39.8% ( ¹ Extraction of fluorine at the stage of calcination in the secondary sublimates and at the stage of Weltzing in clinker (0.95), at the stage of leaching and precipitation with lime (0.94)). The proposed method solves the issue of the withdrawal of most of the fluorine from zinc production into the waste product, at the same time, in the known method, about 55% of the fluorine goes into zinc production during the processing of secondary sublimates, and the other mass is sent to treatment plants.

Table Ways The name of the main stages of the methods Removal of fluorine from secondary sublimates,% Note Famous Calcination - two-stage water-soda washing 45 The bulk of chlorine and 55% of fluorine goes to treatment plants Proposed Calcination - Sulfuric acid leaching - Copper-chlorine cleaning solutions - Cleaning solutions from fluorine with lime - Weltzing fluorinated lime cake with a moisture content of 20-30% 84.8 The bulk of chlorine goes into a marketable product, and fluorine into a dump clinker.

Claims (1)

The method of removing chlorine and fluorine from dusty zinc-containing materials, including calcining the materials to produce sublimates containing chlorine and fluorine, and leaching them, characterized in that the leaching is carried out in a solution of sulfuric acid with separation of the solid from the solution, the solution is gradually purified from chlorine by precipitation monovalent copper and fluorine by precipitating it with lime to obtain fluorine-containing lime cake, it is dried to a moisture content of 20-30% and subjected to Waelz extraction of zinc into Waelz oxide and with translation Fluorine and depleted in calcium clinker.