CN1082615A

CN1082615A - Technology for separating gold from silver without pollution

Info

Publication number: CN1082615A
Application number: CN92109102A
Authority: CN
Inventors: 薛光
Original assignee: Individual
Current assignee: Individual
Priority date: 1992-08-01
Filing date: 1992-08-01
Publication date: 1994-02-23

Abstract

A kind of pollution-free separation of gold from silver has been proposed.The molten sample system of this process using nitric acid-sodium-chlor-potassium permanganate in the polyethylene sample flask, places occluding liquid bath style to heat, and leaches under 108 ℃ of temperature.The gold solution of leaching is a cake of gold with hydrazine hydrate reduction gold, and the silver nitride precipitation of separating out during leaching adopts hydrazine hydrate to reduce.Present method leaches with the chloroazotic acid method that usually adopts, and the method for oxalic acid reduction gold is compared, have simple to operate fast, save reagent, brownout, less investment, and free from environmental pollution, be applicable to the separation of gold dust, middle gold and silver, have tangible economic benefit and social benefit.

Description

Technology for separating gold from silver without pollution

The present invention relates to the pollution-free separation of gold from silver method, be specially adapted to SEPARATION OF GOLD and silver from gold dust.

At present, separate gold and silver from gold dust, except electrolytic process, also have the method for wet separation gold and silver, this method is to adopt the chloroazotic acid extract technology, adopts solid oxalic acid to restore cake of gold, makes proof gold after founding.Leached mud reduces with yellow soda ash, decomposes the gold and silver alloy with nitric acid again, uses zinc dust precipitation silver then.This method is separated gold and silver.This method is separated the process of gold and silver and has been saved electrolytic process, has improved work efficiency, but has shown through production practice, and the used chloroazotic acid amount of this method is big, and long and contaminate environment of operational cycle awaits improving.

The problem that the present invention is directed to existence has proposed a technology for separating gold from silver without pollution method, selects easy reduction gold and silver technology for use, has reduced cost, shortened the cycle, free from environmental pollution, help health of operators, have tangible economic benefit and social benefit.

The method of first technology method of the present invention-extraction gold realizes by following program.

1, takes by weighing a certain amount of gold dust in the polyethylene sample flask, add a certain amount of nitric acid-sodium-chlor-potassium permanganate and water, add a cover and tighten, place sealing water-bath sample-dissoloing unit, be heated to 108 ℃ and kept 0.5 hour, the gold in the gold dust is leached, form tetra chlorauric acid solution.

2, tetra chlorauric acid solution is moved in the Glass Containers, be heated to boiling, dropwise add hydrazine hydrate, no longer include black reaction to solution, be reaction end, continue to be heated to the cake of gold cohesion.

3, cake of gold is washed after, ingot is cast in the fusing under 1200 ℃ of temperature of oven dry back.

Present method hydrazine hydrate add-on is 120% of a theoretical value.

Method of the present invention is cleaned the back under 120 ℃ of temperature dry 1 hour with cake of gold with tap water, and after cooling by following ratio adding saltpetre and borax: 1: 0.01: 0.03, ingot was cast in melting under 1200 ℃ of temperature.

Second technology method of the present invention-method of extraction silver is to realize by following program.

1, will extract the later residue of gold and wash with water totally, add 1: 1 ammoniacal liquor with the silver chloride in the dissolved residue.Solution is filtered residual gold carry out the leaching second time.

2, filtrate is placed being heated on the electric furnace boils adds 1: 1 hydrochloric acid, make the silver in the solution change into the silver chloride white precipitate.

3, the silver nitride precipitation that filters out is put into beaker and added hydrazine hydrate, silver mirror reaction takes place, make argent, clean and then cast silver ingot in 1100 ℃ to immersion precipitation.The amount that adds saltpetre and borax during founding in silver powder is 1% and 3% of this weight.

The present invention compared with existing " chloroazotic acid leaching, oxalic acid reduction separate the gold and silver method " has following advantage:

1, simple to operate fast, the leaching time of present method only be 1/3 of a ratio method, and the recovery time only is 1/6 of a ratio method, can improve work efficiency 3-5 times.

2, present method is saved reagent, brownout, and cost is low, and 5000 liang of gold of annual production are calculated, and present method investment cost is associated with thousand yuan, and ratio method is 1.2 ten thousand yuan.

3, present method production cycle is one day, ratio method three days

4, present method control terminal point is accurate, and the method for the excessive hydrazine hydrate of utilization adding can make the golden Restore All in the solution, and the residual gold in the solution is 0.01 milligram.Residual gold in the ratio method solution is the 0.02-2 nanogram range.

5, extract the purity of gold and silver, rate of recovery contrast.

Ratio method of the present invention

Gold purity 99.99% gold medal purity〉99.9%

Silver purity 99.9% silver medal purity 99.9%

Gold recovery 99.98% gold recovery 99.98%

Silver raising recovery rate 99.96% silver raising recovery rate 99.96%

Application example

1, extract the example of gold:

(1) takes by weighing 30 gram gold dusts (Gold Content is 84%, and silver content is 12%, and impurity is 4%) in 300 milliliters of polyethylene sample flasks, add 15 milliliters of nitric acid, 30 gram sodium-chlor, 1.5 gram potassium permanganate, 50 ml waters shake up, add a cover, tighten, place occluding liquid bath style (can hold 40 sample flasks), the energising heating, after 30 minutes, temperature reaches 108 ℃, keep outage in 30 minutes, placed 30 minutes, take out opening, add water to 300 milliliters, stir evenly, static 2-3 hour.In acidic medium, the CL of solution can be produced the chlorine of nascent state by potassium permanganate oxidation, and the chlorine of nascent state has strong oxidizing property, gold and silver can be dissolved.

Its reaction formula is as follows:

Nitric acid is strong oxidizer, the CL in the oxidable solution of part nitric acid ^-, the chlorine of generation nascent state strengthens molten golden ability.

2, the solution after static is bled filtration under diminished pressure, water thorough washing residue, and move in the thermostatic drying chamber in 120 ℃ of constant temperature dry 1 hour down.

3, filtrate is forwarded in 3000 milliliters of Florence flasks, place heated and boiled on the electric furnace, dropwise add hydrazine hydrate reduction gold with transfer pipet, add fashionable solution reaction fierceness, this moment, tetra chlorauric acid was reduced into cake of gold, and its reaction formula is as follows:

Be reduction fully when adding hydrazine hydrate solution no longer produces black, continue to heat half an hour, cake of gold is condensed fully, solution becomes is clear.

5, whether complete for checking reduction, the gold in the reduced liquid that adopted no flame atomic absorption spectrometry, the gold in the reduced liquid only is 0.01 milligram after measured, also can adopt the Resorcinol method to test, method is as follows: draw 5 milliliters of reduced liquids, in the colorimetric cylinder that is added with 0.05 gram Resorcinol, after jumping a queue, vibrate tens times, static 1 minute, there is not colour-change to show that tetra chlorauric acid is reduced into cake of gold fully.

Resorcinol check gold reaction equation is as follows:

The gold that is reduced out is reddish brown precipitation, and the benzoquinone of generation is sky-blue.This law colour-change is obvious, contains the 0.02-2 milligram hour in solution, then can detect significantly.

6, the cake of gold that restores is bled filtration under diminished pressure for several times with the warm water washing, placed 120 ℃ of thermostatic drying chambers dry 1 hour, the cake of gold 25.42 of weighing after the taking-up cooling restrains, the gained cake of gold is placed plumbago crucible, add 0.25 gram saltpetre and 0.75 gram borax in High Temperature Furnaces Heating Apparatus, be warmed up to 1200 ℃, constant temperature 5 minutes, coming out of the stove makes ingot 24.20 grams, and purity is 99.99%.

In the fusion process, the acidic component B in the borax ₂O ₃Can form borate tailing with the trace metal oxide compound in the cake of gold, generate the eutectic borate with alkaline-earth metal.Also contain alkaline components Na in the borax simultaneously ₂Generate Sodium Tetraborate behind the O, it and silica reaction.Borax about 700 ℃ almost can with all oxide compound chemical combination, can remove various trace impurities in the cake of gold so add borax.

A small amount of iron trichloride in the cake of gold adds saltpetre, can remove this oxidation of impurities.

Extract the example of silver:

1, example 1 is extracted the later residue of gold and wash with water totally, add 1: 1 ammoniacal liquor with the silver chloride in the dissolved residue, its reaction formula is as follows:

Solution is filtered, and residual gold carries out the second time and leaches.

2, filtrate is changed in the beaker, be heated on electric furnace and boil, slowly add 1: 1 hydrochloric acid, the limit edged stirs, and makes the silver in the solution change into white silver nitride precipitation, after 10 milliliters of amounts, places clarification, and its reaction formula is as follows:

Filter with gradient method, water is washed till neutrality with precipitation.Precipitation is transferred in the beaker, is added hydrazine hydrate liquid, place and silver chloride reduction was silver in about 30 minutes to precipitating complete submergence, its reaction formula as

Reductive silver is leached, cleans, puts into plumbago crucible, and after the drying, adding 0.4 gram saltpetre and 0.12 gram borax place High Temperature Furnaces Heating Apparatus, in 1100 ℃ of meltings 5 minutes, come out of the stove, and make silver ingot 3.598 grams in 120 ℃ of thermostatic drying chambers, and its purity is 99.9%.

Claims

1, proposes a kind of nitric acid-sodium-chlor-potassium permanganate pollution-free separation of gold from silver of using, be specially adapted to from gold dust, separate gold and silver.It is characterized in that adopting nitric acid-sodium-chlor-potassium permanganate system, under heating condition, leach,, under 1200 ℃ of conditions, smelt with the hydrazine hydrate reduction.

2, the method for claim 1 is characterized in that every extraction 10 gram gold dust processes are that 5 milliliters of nitric acid-10 gram sodium-chlor-0.5 gram potassium permanganate leach under sealing condition.

3, the method for claim 1 is characterized in that the hydrazine hydrate add-on is that 1 gram gold adds 0.65 milliliter of hydrazine hydrate, is 120% of theoretical value.

4, the method for claim 1 is characterized in that washing cake of gold with water back dry 1 hour cooling back under 120 ℃ of temperature adds saltpetre and borax, and its weight ratio is 1: 0.01: 0.03, and founding becomes ingot under 1200 ℃ of temperature.

5, proposed a kind of method, it is characterized in that: at normal temperatures silver nitride precipitation has been used hydrazine hydrate soaking and reducing Cheng Yin, after the cohesion of placement precipitation, filtered out silver with hydrazine hydrate reduction silver.

6, method as claimed in claim 5 is characterized in that the hydrazine hydrate add-on is 120% of silver.