DE1924546C3 - Process for the processing of ammonia slag - Google Patents

Description

The invention relates to a method for processing ammonia slag of different origins and different degrees of hydrolysis, in particular for the production of zinc chloride.

During the galvanization of iron parts, ammonia slag occurs, the majority of which consists of zinc monoamine chloride, Zinc oxychlorides, zinc residues and impurities from the galvanizing process exist. Since these slags are produced in considerable quantities, it is economically viable to process them and recycle them.

So it is known, for example, this ammonia slag reconditioned by treatment with acid and used as a raw material for lithopone production.

It is also known from US Pat. No. 2,145,817 to obtain a pure zinc tetrammine chloride solution [Zn (NH _{4 I 4} Cl ₂ ]) from ammonia slag by ammoniacal leaching. However, this is not the object of the present invention.

The ammonia slag can also be leached with water in order to obtain more or less pure zinc chloride and to obtain solutions containing ammonium chloride. This used to be different from the LeBlanc soda process Well-known leaching process according to Shank has proven its worth. This leaching process is e.g. B. in the encyclopedia der technical chemistry by Ullmann, 2nd edition, volume 8, p. 72 described.

However, this Shank's method can no longer be carried out easily today, since the slags in very different properties can be delivered. The hydrolysis of the main component zinc monoamine chloride has progressed to different degrees, so that besides glassy material also greasy and gritty material accumulates. Leaching in a known manner is also going through in recent times increasing levels of aluminum and silica make it difficult and sometimes impossible.

The invention is based on the object of ammonia slags of different degrees of hydrolysis and of various origins in an economical way by leaching so that one technically Usable solution containing zinc chloride and ammonium chloride is obtained and a practically ammonium chloride-free one Zinc hydroxide or zinc oxychloride remains as a residue. This residue can be beneficial can be used for the production of pure zinc chloride.

This object is achieved according to the invention

solves that one mixes the ammonia slag in such proportions, that existing zinc chloride is converted into zinc ammonium chloride and zinc oxychloride and the material, which has been crushed to a grain size of 3 to 30 mm, is placed in a leaching container, in

which it is leached discontinuously with zinc chloride and ammonium chloride-containing alkalis with a concentration falling from 30 to 5 ° ο and a ^{temperature rising from 20 to 80 1} C in 5 to 60 minutes, the leaching liquid being led in push-pull

ao will.

To explain the method according to the invention, reference is made to the method described in A b b. 1 reproduced flow chart referenced:

The salmiak liquor to be processed

ken consist mainly of zinc monoamine chloride. This material is hygroscopic and hydrolyzed depending on; h storage and storage time to different degrees The material is initially greasy, woKi this goo from the hydrolysis products

of zinc monoamine chloride, in particular of zinc chloride and zinc oxychloride. In this condition, the material cannot be ground, sieved or sifted in conventional mills, as it builds up in the mill and clogs sieving and sifting machines. With further hydrolysis, the material takes on a looser texture and now consists largely of zinc oxychloride.
Ammonia slag is used for processing and

different degrees of hydrolysis and sometimes different compositions. This incoming Raw materials are stored separately depending on their nature and are shown in the flow chart designated as 1, 2 and 3.

In order to come to a grindable, grindable and leachable good, it is necessary. Materials glassy, greasy and greasy texture to be mixed in such a proportion that free Zinc chloride is converted into zinc ammonium chloride and zinc oxychloride.

This mix can now be ground to a grain size that is optimal for leaching. The grist is sieved and separated into three fractions:
The material with the optimal grain size for leaching of 3 to 30 mm is filled into the leaching tank. The coarser material, which has a particle size of more than 30 mm, goes back into the grinding and crushing process, since leaching such large particles would take too long and would only take place incompletely. The fine material with a grain size of <30mm. which would have an unfavorable effect on the porosity of the bulk leaching layer, is added to the mixture and worked up there again to a grindable product.

According to the invention, the leaching is discontinuous with alkalis of decreasing concentration and increasing temperature. First, about 30% zinc chloride and ammonium

chloride-containing lye, which has a temperature of 20 ³ C, is fed into the leaching tank. The liquor concentrates to about 40 to 45% and can be used in this form, for. B. processed to zinc ammonium chloride.

The second leaching takes place with a lye of about 15 ⁰ Zo and 30 ° C. This lye is concentrated to about 30% and, in this discontinuous mode of operation, serves as the first leach for leaching fresh material. In a third stage, the auszulaugende material is "C treated with a 5 ^o / o liquor at about 50, with its concentration to etws 15 ^a / o increased. Finally, the auszulaugende Good about 80 ^c C warm condensed water is flushed, wherein a This method of working ensures that a highly concentrated zinc ammonium chloride solution is obtained which can be further processed immediately.

It is of particular importance for the feasibility of the method according to the invention that in this procedure, the formation of slimy clogging zinc oxychloride is avoided, so that the Bulk forms an excellent porous filter layer.

Another feature of the invention

ScWiUe lye is pressed. By pressing in the lye is loosened the fill and the leaching favored. After 60 minutes at the latest, it reaches 9 ^ 0 of the possible concentration has shown that in the inventive method

£ 5? S

the density simply

A large number of leaching tanks in front of the roof the last treatment remains a leach material, which practically does not contain ammonium chloride contains more and mainly consists of zinc oxulhydrate and zinc oxychloride. This material can be processed into pure zinc chloride.

example

Three ammonia slags are passed through a crusher at the same time and as proportionally as possible.

Analytical composition of the slags

Slag I.
Slag II
Slag III

72.41 ⁰ O l 6.3%, 27 ° o

53.15 ° 0 8.3 ° / 0.80 ° 0

52.25 ° 0 10.2 ° Ό 10.01 ^{0 E}

Zn

NH ₄ Cl

H ₂ O

Zn

NH ₄ Cl

H ₂ O

Zn

NH ₄ Cl

H ₁ O

Texture gritty, gritty, high metal content,
not hygroscopic

Poured glassy in drum, hygroscopic
gray, wet-greasy, plast. Chunks

3 t of slag I, 5.5 t of slag II and 2 t of slag III were used. 10.28 t of broken, dry, usable slag were recovered with 10 t of solids and 0.28 t of H ₂ O and 0.321 oversized grain (almost exclusively metallic Zn) flowed back.

The leachable material has now been leached according to the claimed method. The quantity flow diagram gives In Fig. 2 the input and output material amounts in a somewhat simplified form.

1 sheet of drawings

Claims (2)

Patent claims: 1. Process for the processing of ammonia slag of different origins and different Degree of hydrolysis for the production of zinc chloride, characterized in that the ammonia slag is obtained in such proportions mixes that existing zinc chloride is converted into zinc ammonium chloride and zinc oxychloride and the material, crushed to a grain size of 3 to 30 mm, in leaching tanks fills, in which it is discontinuous with zinc chloride and ammonium chloride-containing alkalis of 30 to 5% decreasing concentration and from 20 to 80 "C increasing temperature in 5 to 60 minutes is leached, with the leaching liquid is led in push-pull. 2. The method according to claim 1, characterized in that the liquor during the leaching is circulated and withdrawn in opposite directions only after the desired concentration has been reached will.