CN102373338A

CN102373338A - Method for extracting metallic silver from silver chloride sediment

Info

Publication number: CN102373338A
Application number: CN2010102581538A
Authority: CN
Inventors: 王德全; 李岩松; 施善林; 郭闯
Original assignee: CHINA NONFERROUS METAL MINING (GROUP) Co Ltd; SHENYANG RESEARCH INSTITUTE OF NONFERROUS METALS
Current assignee: CHINA NONFERROUS METAL MINING (GROUP) Co Ltd; SHENYANG RESEARCH INSTITUTE OF NONFERROUS METALS
Priority date: 2010-08-20
Filing date: 2010-08-20
Publication date: 2012-03-14

Abstract

The invention discloses a method for extracting metallic silver from silver chloride sediment. The method is characterized in that: silver chloride slag is subjected to dechlorination conversion by using sodium carbonate, and the dechlorinated silver slag is smelted. The method comprises the following steps of: (1) mixing the silver chloride sediment and anhydrous sodium carbonate ingredient in an amount which is 40 to 50 percent of the mass of the silver chloride sediment uniformly, roasting, crushing the reaction materials after roasting, stirring and leaching by using hot water, performing liquid-solid separation, and obtaining metallic silver slag and a sodium chloride solution; and (2) drying the metallic silver slag, adding sodium nitrate and sodium carbonate, fully mixing uniformly, transferring the materials to a graphite crucible, smelting, taking out the totally smelted materials out of the crucible, stirring the melt by using an iron rod so that the melt is fully reacted and demixed, smelting continuously, taking out the melt out of the crucible after smelting, pouring the melt into a pig mold, cooling, knocking off the dross, and obtaining metallic silver ingots. By the method, the problems of long process flow, low straight yield of silver and the like in a wet method are avoided, and the influence caused by volatilization of chlorides during high-temperature smelting is solved; and the cost in the method is much lower than that in a method using sodium hydroxide.

Description

A kind of method of from the silver nitride precipitation thing, extracting argent

Technical field

the present invention relates to a kind of process for extracting of argent, particularly relate to a kind of method of from the silver nitride precipitation thing, extracting argent, belong to the precious metals metallurgy technical field.

Background technology

silver nitride precipitation method is to extract and reclaim the main enrichment means of argent with wet method.In waste liquid, reclaim in the process of silver, at first silver in the solution is changed into silver nitride precipitation usually.Argentiferous solid materials, in the wet processing process like copper, lead anode slurry, when leaching base metal with hydrochloric acid soln, the silver in the material is converted into the Silver monochloride insolubles.How from the silver nitride precipitation thing, to extract argent is the gordian technique in the silver-colored production process.

are present, and the treatment process of silver nitride precipitation thing mainly contains ammoniacal liquor leaching-hydrazine hydrate reduction and two kinds of technologies of S-WAT leaching-formaldehyde reduction.Adopt the ammonia soaking technology, the direct yield of silver can reach about 98%, but needs a large amount of the use that the ammoniacal liquor that volatilization is strong, smell stimulates arranged during operation, and operating environment is poor, is prone to human body and environment are worked the mischief; And when adopting the S-WAT extract technology,, soak silver-colored weak effect because there is solubility limit in S-WAT; The direct yield of silver can only reach about 96% approximately; And temperature descends and to be prone to make the S-WAT crystallization to separate out, and line clogging takes place, and it is bigger that technology is influenced by weather and changes of seasons.In addition, wet processing Silver monochloride slag problems such as also big, the long flow path of ubiquity reagent consumption, wastewater flow rate be big.Silver monochloride adds the soda ash melting also can obtain argent, but because Silver monochloride significantly volatilized in time more than 700 ℃, and the damaed cordition of silver is serious, and the easy polluted air of chloride-sublimation, the application of this method is restricted night.Document announcement is arranged, adopt sodium hydroxide solution that silver nitride precipitation is leached, can transfer Silver monochloride to oxide compound, carry out melting then, but the sodium hydroxide price is higher, transforming problem such as not thorough needs solution.

Summary of the invention

the object of the invention just is to overcome the above-mentioned deficiency that prior art exists; To the existing problem of from the silver nitride precipitation thing, extracting the existence of argent method, develop the novel method that a kind of " yellow soda ash dechlorination-pyrometallurgical smelting " handled the silver nitride precipitation thing.The present invention adopts thermal process to handle the silver nitride precipitation thing and extracts argent, has avoided problems such as wet processing long flow path, silver-colored direct yield are low; With yellow soda ash is that dechlorinating agent carries out carrying out melting after the dechlorination to Silver monochloride, the influence that chloride-sublimation is brought when having solved high melt, and cost is more much lower than adopting sodium hydroxide.

The technical solution that the present invention provides is: the method for extracting argent in this silver nitride precipitation thing; Be characterized in that with yellow soda ash the Silver monochloride slag being carried out dechlorination transforms; And dechlorination silver slag carried out melting; Constitute by following steps: the soda ash light batching mixing of (1) silver nitride precipitation thing and its quality 40%-50%, then batch mixing is carried out roasting in 450-550 ℃ of rotary kiln, following reaction then takes place in material:

roasting time is 2-3 hour, and roasting finishes, and reaction mass is ground; Use the hot water agitation leach, dissolve and remove sodium-chlor, liquid-solid separation; Obtain argent slag and sodium chloride solution, the argent slag is used for desilver, and sodium chloride solution reclaims sodium-chlor through evaporate-crystallization.

The argent slag oven dry that (2) obtain step (1); Allocate the SODIUMNITRATE of 1%-5% and the yellow soda ash of 3%-5% into, fully change plumbago crucible over to behind the mixing, carry out melting at 1000-1100 ℃; Material melts the back fully and takes out crucible; Stir melt with iron rod, it is fully reacted and layering, continued melting then 30 minutes.Take out crucible after melting finishes, melt is poured in the pig mold, cooling back knock-off scum silica frost obtains the metal silver ingot.

the present invention compared with prior art, its beneficial effect is: avoided the irritating smell of ammoniacal liquor, the labor operation improvement of terms 1..

2. the flexibility of pair season and weather are strong, and no line clogging situation takes place.

Leaching and the liquid-solid number of times that separates are 3. reduced in , improve silver-colored direct yield.

The dechlorination processing is 4. carried out to the Silver monochloride material before the melting in , has solved volatilization and pollution problem under the Silver monochloride high temperature.

It is dechlorinating agent that yellow soda ash is 5. adopted in , reduces the dechlorination cost.

Specific embodiments

embodiment 1: get the Silver monochloride slag 500g of argentiferous 72.00%, add 200g yellow soda ash, 500 ℃ of revolution roasting in kilns 2h behind the mixing.Material is taken out, and cooling grinds, with 2000ml85 ℃ of hot water agitation leach 1h, liquid-solid separation.With the grey slag oven dry that obtains, allocate 5% yellow soda ash into, 3% SODIUMNITRATE changes plumbago crucible over to behind the mixing, and melting is 60 minutes under 1100 ℃ of temperature.Obtain the metal silver ingot after the cooling, take by weighing weight, and chemically examine.

result: silver ingot quality: 360.40g; Silver ingot purity: 99.23%; Silver direct yield: 99.34 %.

embodiment 2: get the Silver monochloride slag 500g of argentiferous 72.00%, add 250g yellow soda ash, 550 ℃ of revolution roasting in kilns 2h behind the mixing.Material is taken out, and cooling grinds, with 2000ml85 ℃ of hot water agitation leach 1h, liquid-solid separation.With the grey slag oven dry that obtains, allocate 3% yellow soda ash into, 1% SODIUMNITRATE changes plumbago crucible over to behind the mixing, and melting is 45 minutes under 1000 ℃ of temperature.Obtain the metal silver ingot after the cooling, take by weighing weight, and chemically examine.

result: silver ingot quality: 360.60g; Silver ingot purity: 98.87%; Silver direct yield: 99.03%.

embodiment 3: get the Silver monochloride slag 500g of argentiferous 63.15%, add 250g yellow soda ash, 450 ℃ of revolution roasting in kilns 2h behind the mixing.Material is taken out, and cooling grinds, with 2000ml85 ℃ of hot water agitation leach 1h, liquid-solid separation.With the grey slag oven dry that obtains, allocate 5% yellow soda ash into, 1% SODIUMNITRATE changes plumbago crucible over to behind the mixing, and melting is 60 minutes under 1050 ℃ of temperature.Obtain the metal silver ingot after the cooling, take by weighing weight, and chemically examine.

result: silver ingot quality: 317.08g; Silver ingot purity: 98.68%; Silver direct yield: 99.10%.

Claims

1. extract the method for argent in the silver nitride precipitation thing, it is characterized in that with yellow soda ash the Silver monochloride slag being carried out dechlorination transforms, and dechlorination silver slag is carried out melting, constitute by following steps:

(1) soda ash light of silver nitride precipitation thing and its quality 40%-50% batching mixing carries out roasting with batch mixing then in 450-550 ℃ of rotary kiln, and following reaction then takes place material:

Roasting time is 2-3 hour, and roasting finishes, and reaction mass is ground, and uses the hot water agitation leach, dissolves to remove sodium-chlor, and liquid-solid separation obtains argent slag and sodium chloride solution, and the argent slag is used for desilver, and sodium chloride solution reclaims sodium-chlor through evaporate-crystallization;

(2) the argent slag oven dry that step (1) is obtained; Allocate the SODIUMNITRATE of its quality 1%-5% and the yellow soda ash of 3%-5% into, fully change plumbago crucible over to behind the mixing, carry out melting at 1000-1100 ℃; Material melts the back fully and takes out crucible; Stir melt with iron rod, it is fully reacted and layering, continued melting then 30 minutes;

Take out crucible after melting finishes, melt is poured in the pig mold, cooling back knock-off scum silica frost obtains the metal silver ingot.