Basic terms: gold, gold extracting factory, hydrometallurgy, hypochlorite, chlorine, silver

Technology of gold extracting be cyanides provides use of harmful for human and dangerous for environment reagent, potassium cyanide, that is toxin of the 2-nd class of danger as accumulative active substance. Even minimal wastes act sufficiently on to environment. For neutralization of potassium cyanide has been used calcium and sodium hypochlorite or hydrogen peroxide. This a reason for mixture excavations, which contain sufficient amount of difficultly recyclable solution (volume of reservoirs is millions of cubic meters with appropriate cost for storage of wastes). It covers partially a problem of main effluent of potassium cyanide but doesn't resolve an evaporation of cyanide and its throw into atmosphere.

Use of sodium hypochlorite and chlorine for gold extraction is already known to scientists. These methods has been exercised under experiments and enlarged laboratory tests. The problem is deeply researched. Publications are available. The multi-functional 5lpha” complex is designed to implement new technology in industry. Equipment of this complex is suitable for all technical tasks in chlorine gold extracting technology.

One of perspective gold extracting methods a heap leaching by 5lpha” complex. Gold extracting value achieves 98 – 99,3% by electrolysis, relative electro-energy consumption varies from 40 till 170 kW/h for 1 kg of regenerated gold. Electrolytic gold extracting from hypochlorination pulps of various gold-containing concentrates is studied by scientists.

Chlorine technology provides sufficient reduce of material, labour and energy consumptions.

Gold and silver extraction has been made by 5lpha” complex accordingly to technology without harmful wastes into environment and on to work zone air as well.

The above described technology has been used previously for gold, silver extracting and for metal extraction from ore with low and medium amount of regenerating admixtures, in processes of heap leaching and for under-earth gold mining by hole drilling (extraction value from 86 till 99% of total massive).

Technological scheme

Process of gold extracting is a multi-stage technology: dissolving – accumulation - filtration – electro-oxidizing – adsorption – electrolysis. Technological equipment line consists of next machinery:

– adsorber,

– electro-flotation machine,

– ion-exchange section,

– electrolysis apparatus,

– storage tanks,

– reagent preparation modules,

– accessory equipment.

Low hazard substances are usable as reagents for chlorine gold extracting. These are as following:

– sodium chloride (the 5thclass of danger),

– gold extractor (the 5thclass of danger),

– gold absorber (the 4thclass of danger).

Technology description

Production output effectiveness is 1,5 t/year and more at energy consumption – 4,2 kW, square isn't more than 50 m??, reagent consumption is 50 kopecks per 1 g of gold. Metal transferring (Au, Ag and other) from gold-containing raw material into solution goes under natrium hypochlorite NaClO. Approximately 50 mg gold has been extracted by each natrium hypochlorite liter. For more effective gold extraction extracting reagent has been put into solution, which enables making ore wet and intensifies gold dissolving, delays gold sediment on ferrous admixture and sulfide minerals. Process goes through the irrigation line of the gold-containing mineral mass. In leach solutions with oxidizing substance iron becomes passive and stays in heap. Sulfide ore has been oxidized faster. Ore with sufficient amount of sulfides and iron may be proceeded by 5lpha” complex for non-chloride oxidizing of admixtures (iron, sulfide ore), able to oxidation, by directing solution onto clamp and previous aeration of electrolyte during electrolysis process. By means of dissolved oxygen, oxygen-containing compounds and oxidizing substance sulfides and iron scrap has been oxidized. Such substance provides admixtures oxidizing without dissolving gold and silver.

Solution with gold concentration about 50 mg/l has been drifted into storage tank and then has been directed into adsorber by drain pump. In filter with leach substance suspended elements and heavy metal have been separated and colloid iron has been coagulated in contact. After that solution merges into electrical flotation machine, where not enough coagulated colloid metal elements have been transferred into suspension and flotated. Then solution, which mostly contains chloride compounds of gold and silver, goes to absorption by ion exchanger. Anion compounds have been adsorbed anion exchanger.

From filter (exchanger) precious metal has been separated by gold adsorber.

At that moment a charge has been alternated. Anion compounds have been transferred into that of cation, due to this condition they have been eluted totally from filter.

Cation compounds of gold and silver may be used already for electro precipitation on cathode. Under current at the negative charge of cathode metal elements have been precipitated on electrode.

For this processing a regeneration module as hermetical stable machinery has been practiced. Electrode potentials of gold and silver extraction at concentration in eluate 1gram molecule weight/l are equal to -1,089 V and -1,788 V accordingly.

Reagents preparation

Gold extractor solution preparation

In reservoirs for reagent mix a water solution of gold extractor shall be prepared. Prepared solution of gold extractor has been directed by metering pump into the reservoir.

Sodium hypochlorite solution preparation

Natrium hypochlorite is a result of natrium chloride solution electrolysis. Advantages of direct natrium hypochlorite producing from natrium chloride are relative low consumptions, simplicity of process, possibility of use of technical raw sodium chloride.

In unit of reagent preparation a concentrated water solution of natrium chloride has been produced.Solution has been directed by metering pump

into reservoir for reagent mixing, where gold extractor solution has been mixed with natrium chloride solution. After that this solution has been put into electro reactor by chemical pump. From collection tank elaborated solution of natrium chloride goes hereto for regeneration. In electro reactor created solution of hypochlorite merges into reservoir, from where it has been directed for irrigation of gold containing raw material by chemical pump.

Gold adsorber solution preparation

In unit of reagents mixing a concentrated water solution of gold adsorber has been produced. For dissolving process intensification device is outfitted with heating mechanism to enable water to better dissolving. Gold adsorber has been dissolved at intensive mixing process. Prepared concentrated solution of gold adsorber goes by chemical pump into reactor, where required concentration of solution has been normalized. Then, solution goes by dosing pump to the ion exchange tank, which is made as 5lpha-7xc” module (free-flow version). Solution of gold adsorber has been regenerated in process of electrolysis (method of electrolysis as KNOW-HOW). Regenerated solution has been used repeatedly.

Adsorber washing procedure

Polluted sorbent of adsorber has been washed with natrium hypochlorite solution, which has been given by chemical pump in bottom-up direction with recommended by sorbent producer most appropriate method and rapidity. After washing solution with sediment merges into ore mineral mixture. Sediment in mixture becomes condensed due to filtration through ore.

Chlorine utilization

Created from chloride compounds of gold and silver after electrolysis in reactor chlorine goes to pipeline before electrolysis unit. By such way chlorine has been blocked for getting into environment and on to air of processing zone.

Keeping in readiness of leach substance concerning all the process is a required condition for ecological protection of production excluding gas throws. For silver extracting from elaborated wastes mobile version of 5lpha-Argentum” is developed. Production output of such mini-device is up to 70 dm3  solution per hour, what results as 0,5 kg silver per day.


Key words: gold, gold extracting factory, hydrometallurgy, hypochlorite, chlorine, silver

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