HU198654B - Process for producing zinc salts from zinc sludge and formed with inorganic carboxylic acid or with organic carboxylic acid having 1-4 carbon atoms - Google Patents

Abstract

Waste zinc muds are washed with water until neutral and salt free, centrifuged and the wet centrifuge cakes dissolved in monovalent and polyvalent inorganic or organic acids e.g. hydrochloric, nitric, sulphuric acid, etc., or formic acid, acetic acid, etc. Any heavy metal salts present in the solns. are oxidised with hydrogen peroxide, chlorine etc., and pptd. with zinc-oxide. The solns. are filtered. - The clear soln. is conc. in vacuo, or evapd. to dryness, alternatively the conc. soln. is crystallised. Any organic cpds. decomposing during concn. are oxidised with hydrogen -peroxide, chlorine, or finally with alkali-chlorate or alkali-perchlorate.

Description

This application relates to a process for utilizing waste zinc sludge to recover various inorganic and organic zinc compounds. Thus, colorless anhydrous zinc chloride, crystalline zinc sulfate, zinc acetate and the like. the preparation.

The process according to the invention contains so-called so-called "waste" containing basic zinc carbonate, sodium carbonate, sodium chlorate and unknown amounts of tar-like substances, which are produced in the production of ion-exchange resins and which cannot be utilized. zinc slurry can be used as a secondary raw material to produce various inorganic and organic zinc compounds.

Zinc sludge precipitated during the treatment of waste containing zinc chloride as a catalyst in the treatment technology of the ion exchange resin is formed by the precipitation of contaminated basic zinc carbonate.

It is known that there is a growing demand for modern and increasingly urgent environmental protection. These include, for example, the problems of removing and rendering harmless waste and by-products from chemical plants that are not hazardous to the human environment. From the point of view of technical efficiency and cost reduction, ideas, procedures and measures are being promoted both domestically and internationally, which transform the contaminated residues into reusable materials, as opposed to costly underground disposal or incineration.

A simple process for the production of anhydrous zinc chloride required for the production of an ion exchange resin for water softening and for the production of anhydrous zinc chloride from the zinc sludge necessary for the production of an ion exchange resin has not yet been described.

The closest prior art processes known to date include:

(a) German Patent Publication No. 18 16 608 discloses a wet process refinement depletion process comprising the addition of metal zinc to the solution in the form of a fine powder before the ferric ions of the solution are oxidized to hydrogen ferric ion.

(b) The process according to English Patent Publication No. 2,035,983 is prepared from a solution of zinc chloride, which is essentially iron-free and aluminum-free, and has a high concentration of water. The process is characterized by firstly treating a solution of zinc chloride having a pH of 1.5-3 at a temperature of 15-26 ° C and a pressure of 6-48 bar for 1-3 hours and precipitating the iron and aluminum impurities in the form of hydroxides, followed by a second step. In step 5, the mixture is cooled suddenly, the precipitate is washed and filtered. Finally, if necessary, the previous steps are repeated.

(c) French Patent Publication No. 2 273 878 describes a process for recovering metals from metals, in particular zinc, chloride and / or other halides. The process according to the invention is characterized in that, first, the metal scrap material is contacted in a liquid organic phase containing a potassium exchanger, with a soluble organic metal complex. In the second step, the halides and other impurities are removed by washing the organic phase with water or an aqueous alkaline solution. In the third step, the organic phase is finally reacted with a mineral acid to obtain a pure metal salt solution.

It is an object of the present invention to provide a rational solution to a simple industrial process utilizing zinc carbonate or basic zinc carbonate sludge, which can be transformed into unprocessed and environmentally hazardous wastes into various inorganic and organic zinc salts. can be used in the industry in a well known manner.

The present invention is based on the discovery that by appropriate washing, settling, centrifuging and even centrifugation of the crude sludge in a monovalent or inorganic or C 1 -C 4 organic acid, oxidation and precipitation of the heavy metal salts followed by filtration and evaporation of the solution or crystallization. we can produce.

Based on this discovery, the object of the present invention has been solved by a process such that the solids have a solids content of approx. The crude slurry containing 60% (v / v) basic zinc carbonate (2ZnCO3.3Zn (OH) 2) was washed 3 to 5 times with 5 to 10 times water with vigorous stirring and then centrifuged after settling. The still wet centrifuge slurry is dissolved in one or more inorganic or C 1-4 organic acids (such as hydrochloric acid, sulfuric acid, formic acid, acetic acid, etc.). The solution is filtered after oxidation of any heavy metal salts with hydrogen peroxide followed by precipitation with zinc oxide. The clear solution is first concentrated in vacuo and crystallized or, for example, in the case of zinc chloride, evaporated to dryness, heated to approximately 250 ° C. At the temperature of evaporation, due to the decomposition of the organic material present, the material may become discolored or staring. It is then treated with alkali chlorate.

The main advantages of the process according to the invention are the following:

a) Waste from zinc sludge, which is otherwise wasteful, hazardous and environmentally hazardous

-2GB 19864 Β produces, as secondary raw material, colorless and anhydrous or crystalline zinc salts which can be used in a manner known per se without the need for foreign import.

b) As a large-scale technology, it can be easily, cheaply and quickly implemented.

(c) The final product may be used without any further purification or recrystallization in conventional and known manner.

The invention is illustrated in detail by the following embodiments:

Example 1

2450 grams of 2ZnCO3.3Zn (OH) 2 from the manufacture of ion exchange resins, approximately 20 zinc sludges containing basic zinc carbonate, containing 50 parts by weight of basic zinc carbonate, 12% by weight of sodium chloride, varying amounts of alkali carbonate 2 contains organic material of unknown composition, washed with water to neutral pH 25 and desalted, then sedimented and centrifuged. Dissolve 2000 g of washed centrifuged slurry in 1500 ml of 30% hydrochloric acid, leaving 50 g of zinc slurry insoluble. While still warm, 40 ml of a 35 wt% to 30 wt% hydrogen peroxide solution are added and mixed thoroughly. A paste is prepared from 30 g of zinc oxide with a little water and, with stirring, added to the already oxidized zinc chloride solution. The solution was filtered. 2500 ml of a colorless and heavy metal salt-free zinc chloride solution are thus obtained.

The product obtained is initially concentrated under vacuum to about 75% by weight and then concentrated to dryness at atmospheric pressure, raising the temperature to 40-250 ° C. At this temperature, the organic material of the original composition, of unknown composition, decomposes and discoloures the material. To overcome this, 0.01 to 45% by weight of zinc chloride is added in small portions during evaporation.

The final product obtained from 2450 g of sludge yields about 800-900 g of snow-white zinc chloride of 98-99% purity. Melting point 280-50-300 ° C.

Example 2

The slurry washed and purified according to Example 1 was dissolved in 700 g of 96% sulfuric acid and evaporated until crystallization, followed by crystallization to give 1000 g of crystalline zinc sulfate. Melting point 40 ° C. 60

Published by the Office of National Invention, Budapest R-4877 Example 3

The slurry washed and purified according to Example 1 was dissolved in 900 g of 65% nitric acid and evaporated to crystallization, followed by crystallization to give 1300 g of white crystalline zinc nitrate. Melting point 36 ° C.

Example 4

The slurry washed and purified according to Example 1 was dissolved in 800 g of 96% acetic acid and evaporated to crystallization, followed by crystallization to give 1200 g of white crystalline zinc acetate.

Claims (5)

PATENT CLAIMS A process for the production of ion exchange resin from zinc sludge wastes containing at least 60% zinc carbonate and / or basic zinc carbonate from waste water by treating zinc chloride-containing waste water with sodium carbonate or sodium hydrogen carbonate For the preparation of organic zinc salts with C4 carboxylic acids, the crude sludge is washed with water for neutral pH, alkali and salt free, followed by at least a stoichiometric amount of inorganic or organic carbon with respect to zircycarbonate and / or basic zinc carbonate. or in an aqueous solution thereof, optionally up to 5% by weight of hydrogen peroxide, based on the weight of zinc carbonate and / or basic zinc carbonate, and precipitation of the oxidized heavy salts with up to 10% by weight of zinc oxide, filtered and filtered. hile The resulting clear solution is either concentrated and the zinc salt is crystallized by addition, as is known in the art, to one or more parts by weight of alkali chlorate up to 0.1% by weight, based on the weight of zinc carbonate and / or basic zinc carbonate. evaporate to dryness. Process according to claim 1, characterized in that the inorganic acid is hydrochloric acid. f 3. The process of claim 1 wherein the inorganic acid is nitric acid. A process according to claim 1 wherein the inorganic acid is sulfuric acid. 5. The process of claim 1, wherein the organic acid is a C 1-4 acid.