JPS6070132A - Noble metal recovery - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for improving the recovery of precious metals from noble metal containing compositions. In particular, the present invention uses base metal materials such as
The present invention relates to an improved method of treating waste streams from precious metal recovery processes to produce substantially metal-free waste streams that are environmentally advantageous and have increased separation.

In the manufacture of various relatively high cost metal articles, such as jewelry, precious metals, either as pure metals or as alloys, are mechanically bonded to one or more base metals or base metal alloys. to form metal stock. Such metal stock will hereinafter be referred to as bimetallic material to distinguish it from these alloys.
ls). Such gamut stocks have one or more of their surfaces VC-attached precious metals. Besides jewelry, these bimetallic stocks are also useful for manufacturing table ashtrays, electronic circuitry, components, mechanical parts, etc. The formation of such articles varies in shape, size and layered structure. Generates a large amount of scrap.

It is economically advantageous to recover as much precious metal as possible from such scrap.

Currently, the most widely used method for recovering precious metals from scrap is electro-refining of base metals, metals (usually copper) and subsequent electrolysis of the precious metals from the insoluble slime produced by the electro-refining. Including electro winning. In such processes, precious metal scrap is melted to form an alloy whose main component is (alternatively) copper. This alloy is then used as an anode in an electrolytic cell with a sulfuric acid-copper sulfate electrolyte. The initial cathode of the cell is high grade copper on which is further plated essentially pure copper electrochemically dissolved in the electrolyte from the anode. Precious metals that are insoluble in the electrolyte fall to the anode as fine mud or slime. molecule"(
After 1, precious metals undergo a number of additional purification steps before they are used commercially.

Due to the complexity and cost associated with prior art processes, other research into methods of recovering precious metals from scrap has resulted in a number of related and unrelated processes. Recently, a simplified method for recovering precious metals from scrap has been proposed in U.S. patent application Ser. 4th. ．． No. 261,738. The above patent describes bimetallic materials by leaching (leα
The leachate is subjected to an ammoniacal solution containing reactive oxygen.
water 1'l-= of ammonium salt in lu-tion)
? ? A method of recovering precious metal mounds from bimetallic materials, including those formed from 'i' liquids, is disclosed. Base materials that make up scrap
)-enriched exudate liquid (1eacha, te 1iqui
d) is obtained. The precious metal is recovered essentially unchanged from the reaction vessel. Aqueous encapsulating exudate
The leachate liquid, referred to as spregnantleαch 1 equor, is then thermally decomposed to precipitate the base metals as recoverable solids and form condensable vapors, mostly water and ammonia, which are recovered. Precipitated base metals are recovered using a precipitation solution (precipitσ
tionliquor) and the remaining aqueous waste liquid stream is then disposed of. This aqueous waste stream may contain undesirably high concentrations of base metals that were not precipitated in previous pyrolysis process steps. For example, in the case of bimetallic materials where the base metals contain copper and zinc, this aqueous waste stream may be poor in both soluble copper and soluble zinc, which makes disposing such a waste stream into the environment. make something intolerable.

Thus, soluble base metal values (5 oleblebαs
It is clear that it would be desirable to have an improved method for recovering precious metals from bimetallic materials, where water substantially free of emetalυα1ues) produces a waste stream.

It is therefore an object of the present invention to provide an improved method for recovering precious metals from bimetallic materials that removes high soluble base metal values in the aqueous waste stream of the process.

Another object of the present invention is to increase the amount of non-base metals recovered from prior art methods of recovering precious metals.

Another object of the present invention is a simple and efficient method for removing base metal values from aqueous waste streams containing such base metal values and recycling said base metal values into a closed loop system within a precious metal recovery process. The goal is to provide the following.

These and other objects of the invention are particularly explained in the following detailed description of the preferred embodiments.

According to one aspect of the invention, there is provided a method for recovering a precious metal in pure or alloyed form from a bimetallic material containing at least one base metal, comprising: 1. an ammoniacal solution containing reactive oxygen; leaching the bimetallic material with an aqueous leachate comprising an ammonium salt therein to form an aqueous encapsulating leachate and a precious metal; 2. removing the precious metal from the encapsulating leachate; 3 steaming the encapsulating leachate. 4. pyrolyzing the base metal, thereby precipitating the base metal; and 4. filtering the base metal, thereby forming an aqueous waste stream and a base metal residue. to form a carboxylic acid-type ion exchange resin that has absorbed base metal values and an aqueous waste liquid stream that is substantially free of base metal values, b. contacting a carboxylic acid-type ion exchange resin that has absorbed valuables with at least a portion of the aqueous leachate, thereby desorbing the base metal values from the ion exchange resin, and adding the base metal values to the aqueous leachate; And an improvement is provided comprising using the aqueous leachate in the process of recovering C5 precious metals.

According to another aspect of the invention: 9- An apparatus for recovering precious metals in pure form or in the form of alloys from a bimetallic material comprising at least one base metal element (leaching reactor) means for supplying a bimetallic material, an aqueous leachate, and reactive oxygen to the leaching reactor means; means for forming an entrained leachate containing a base metal in solution; and separating noble metals from the entrained leachate. means for conveying the entrained leachate from the leaching reactor means to the steaming reactor means; means for steaming the entrained leachate to precipitate base metals; and the steamed aqueous waste. An improvement is provided in an apparatus comprising means for separating the base metal from a substance.

Said improvement comprises: a. a carboxylic acid type ion exchange means; b. conveying said steamed encapsulating leachate from said steaming reactor means to said carboxylic acid type ion exchange means to remove base metal values; a means for forming an aqueous waste liquid substantially free of adsorbed caldenic acid-type ion exchange means and base metal values; and contacting said caldic acid-type ion exchange means with adsorbed C0 base metal values with said aqueous leachate. means for melting to form an aqueous leachate solution containing base metal values; d. means for conveying the aqueous leachate solution containing base metal values to the aqueous leachate means.

In the following detailed description of the invention, the waste liquid filtrate stream treated with the improved method of the invention will be described using bimetallic materials (
It should be understood that it comprises a mixture of metal values derived from the recovery of precious metals, usually obtained from succines 76). As such, these precious metals are those which do not dissolve in the ammoniacal leaching solutions of the prior art processes, namely gold, silver, nolasium, rhodium, platinum, iridium, osmium and ruthenium, and alloys thereof. Conversely, the base metals that serve to form the bimetallic stock and appear in the waste stream are those that are soluble in the ammoniacal leachate. Typically, these metals are copper and various alloys of copper such as brass and bronze, some of whose components form solutions in aqueous ammonia.

Added herein by Kawagyo, October 1, 1979
Referring to FIG. 1, which shows a typical prior art process such as that disclosed in U.S. Patent Application No. 6-081, 006, filed in 1999, it is possible to produce a An aqueous leachate is used to separate the noble metal(s) from the base metal(s) to change the composition. The aqueous leachate typically comprises an ammonium salt formed from an acid substantially free of ions that will complex with precious metals in an oxygen-containing ammoniacal solution. Oxygen is economically supplied by sparging air or oxygen gas.

The nature of the ammonium salt used in the process is a function of the precious metal being recovered.

Thus, in the case of gold or other platinum group metals, crushed ammonium acid, ammonium nitrate or ammonium phosphate can be used, whereas ammonium carbonate is preferred when recovering silver.

As stated above, components consisting of base metals do not dissolve in the aqueous leachate. As such, these insoluble components form a slime (fine powder suspension) in the immersive exudate. Examples of such metals that form slime are tin, bronze, brass and germinium in bronze and Babbitt metals.
lead in man 5 silvers) and antimony in brass.

13- The leaching reaction essentially yields two product streams: a solid-free precious metal and a liquid aqueous leachate containing soluble non-metallic values, called an aqueous encapsulated leachate. After filtration to remove suspended fines, this latter solution is pyrolyzed with steam, which decomposes the soluble base metal ammonium complexes into insoluble metal oxides or carbonates and free ammonia gas and water. Ammonia gas is collected and solid oxides or carbonates are filtered from the steamed aqueous encapsulated leachate. The wet filter cake is easily processed to recover base materials in their elemental form. However, the liquid from the filtration operation (aqueous waste liquid)
Ste 1 equal quantity is usually thrown away. Steaming of leachate containing leachate generally results in a steamed aqueous waste liquid that is not completely free of ammonia, which is likely present as ammine complexes in the aqueous waste liquid. A certain amount of dissolved base metal remains. The actual concentration of these metal values is of course a function of the efficiency of the steam treatment. For acceptable steam processing, the concentration of metal values in the steamed aqueous waste liquid is 1.
00 tnf/l or less.

The improved method according to the present invention, when used in the present invention, provides non-chelating (non-ch, elα-t
ing) with a carboxylic acid type ion exchange resin, thereby removing substantially all of the remaining dissolved base metal values by adsorption onto the ion exchange resin, thereby removing , producing a treated waste liquid filtrate stream that is environmentally acceptable for disposal. Regeneration of the ion exchange resin, i.e. desorption of base metal values, is advantageously achieved by treatment with at least a portion of the fresh aqueous leachate used in the first step to go to the leaching process and leaching the precious metal containing bimetallic material. be done. The loaded resin is demetalized using only an ammoniacal solution and thus is not subjected to acid/base cycling. The resulting leachate is then combined with an aqueous leachate stream and used in a leaching process, or if all of the aqueous leachate is used in such a desorption reservoir.
The resulting leachate is used as is for the leaching process.

The carboxylic acid type ion exchange resin used in this improved process has a polymeric backbone (bαckbone).
It is formed from a synthetic polymeric hydrocarbon with many carboxylic acid groups bonded to it. Other requirements for this resin are that it is a waste liquid p
This means that it is not soluble in liquid streams. The actual chemical identity of the polymer backbone is an important consideration when selecting a carboxylic acid type ion exchange resin. Therefore, polymers of methacrylic acid or acrylic acid are used in the present invention. The resins used in the practice of the invention disclosed herein are commercially available. The chemical composition is not available to the purchaser of the resin. However, an example of a resin that has been successfully used in this method is Amberlite IRC-50.

Furthermore, giant reticular resin (mtxcroreticular
These carboxylic acid group (caτbo-xylic) ion exchange resins described as rttsins are preferably used in this method. These resins have large discrete pores that allow easy removal of high molecular weight ions. Similarly, these removed ions are easily removed from the resin by regeneration. It is to be understood that the resin composition is not disclosed or claimed as part of this invention. Disclosed as part of invention 17 is the use of this type of resin in combination with other phases of the process.

The above process is conveniently carried out at room temperature (around 25°C), although both higher and lower temperatures can be used in the absorption or desorption steps.

It is thus seen that the above-mentioned objects, among those made clear from the foregoing description, are effectively achieved and that modifications may be made in carrying out the method and apparatus without departing from the scope of the invention. It is intended that all matters in the foregoing description be construed as illustrative and not in a limiting sense.

[Brief explanation of the drawing]

Attachment 111m is a flow diagram illustrating one embodiment of the prior art method and the method of the present invention. 18-

Claims (1)

[Claims] 1. A method for recovering noble metal in pure form from a bimetallic material whose base material consists of at least one base metal, comprising: (α) an ammoniacal material containing reactive oxygen; leaching the bimetallic material with an aqueous leachate comprising an ammonium salt in solution to form an aqueous encapsulating leachate and a precious metal; (b) removing the precious metal from the encapsulating leachate; (C)
The leachate is pyrolyzed with steam, thereby precipitating the base metal as a recoverable base metal compound, and (b) the base metal compound is filtered, thereby removing the waste liquid and the residual leachate. a. treating the waste liquid P with a carmenic acid type ion exchange resin to form a treated waste liquid stream substantially free of base metal values dissolved therein; b. Process the carboxylic acid type ion exchange resin from step α into step (
at least one of said aqueous leaching liquids going to the leaching process of a)
in the process for removing the base metal values from the carboxylic acid type ion exchange resin and adding the base metal values to the aqueous leachate and recovering CO precious metals. A method characterized in that it comprises the step of using said aqueous infusion solution containing. 2. The method according to claim 1, wherein the carboxylic acid type ion exchange resin is a polymer of methacrylic acid or acrylic acid. 3. The method according to claim 1, wherein the carboxylic acid type ion exchange resin in step α is selected from the group described as a giant reticular resin.