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Your Location:Home > The main factors affecting the gold Thiourea solution have


Also known as urea thiourea vulcanization, the formula SCN2H4, white glossy rhombohedral, bitter, a density of 1.405 g / cc, soluble in water, aqueous solution is neutral. Thiourea toxicity, non-corrosive, the human body without harm.

Thiourea can dissolve gold as tests confirmed that the presence of an oxidant, gold was Au (SCN2H4) 2+ cation network into shape acidic thiourea solution. Thiourea gold dissolution is electrochemical corrosion process, other chemical equation can be expressed as: Au + 2SCN2H4 = Au (SCN2H4) +2 + e to select suitable oxidant is acidic thiourea gold dissolution of the key issues, the more suitable oxidant is Fe3 + and dissolved oxygen, so the chemical reaction of thiourea gold dissolution can be expressed as: Au + 2SCN2H4 + Fe3 + = Au (SCN2H4) +2 + Fe2 + Au + 1 / 4O2 + H + + 2SCN2H4 = Au (SCN2H4) +2 + 1 / 2H2O thiourea expensive gold dissolution was obtained, according to the level of their gold content, can be iron, aluminum replacement or electrodeposition method Immersion Gold, gold mud smelting obtain crude gold. Gold mud smelting process and the same gold cyanide mud.

 

Thiourea leaching rate of gold dissolution time depends mainly on the medium PH value, type and amount of oxidant, the amount of thiourea, mineral composition and size of the gold particles, leaching temperature, leaching time and leaching technology and other factors.

  

Thiourea in alkaline solution is unstable, easily broken down into sulfide and cyanamide. But thiourea in acidic medium more stable. Therefore, from the viewpoint of stability thiourea, thiourea gold extraction generally used when a dilute sulfuric acid solution as the leaching agent thiourea, thiourea and should pay attention to add acid after the first, in order to avoid local overheating pulp leaving thiourea hydrolysis failure.

 

Medium acidity and thiourea concentration, acidity increase with the concentration of thiourea and lower, at room temperature, the amount of thiourea conditioned medium PH value of less than 1.5 is appropriate, but not too much acidity, otherwise it will increase the amount of acid impurities.


When the need to increase the amount of gold dissolution thiourea oxidant, it is preferable for the manganese dioxide oxidizer, formamidine disulfide, iron salts and high dissolved oxygen. If we can maintain the concentration of dissolved oxygen in the pulp, high iron salts obtained acidic thiourea solution regeneration gold dissolution.


Thiourea as organic complexes in acidic solution can be formed with many metal cations cations networks, in addition to mercury, sulfur Stability of other metal cations network urea, thiourea therefore acidic liquid gold dissolution with high selectivity . But the raw material of copper, bismuth oxide will acid, thiourea complex with reduced Thiourea thiourea effect and increase the amount of raw materials containing higher amounts of acid-soluble substance (such as divalent iron, carbonates non-ferrous metal oxides, etc.) and reducing component increased oxidant and sulfuric acid consumption and decrease the leaching rate of gold. But the harmful effects of copper, arsenic, antimony, lead sulfide minerals of thiourea gold dissolution is small, and therefore acidic thiourea was dissolved gold and silver can be extracted from a complex selective refractory metal mineral raw materials. Gold grain size is one of the factors that affect the gold leaching rate.



Thiourea leach gold dissolution rate increases with a rise in temperature increase, but the thermal stability of thiourea small, high temperature hydrolysis prone to failure, the slurry temperature should not exceed 55 degrees, generally carried out at room temperature thiourea gold extraction.


Gold leaching rate generally increases with increasing amount of thiourea and improve, as thiourea gold extraction mainly by high iron ions as an oxidizing agent, high concentration of iron ions in solution much higher than the high concentration of dissolved oxygen and can be adjusted, so thiourea gold dissolution the higher the concentration of thiourea, sulfur dosage varies with the raw materials of gold, its consumption (kg / t) of a few kilograms to several tens of kilograms.


Gold leaching rate generally increases with leaching time increased. Gold leaching rate of leaching technology related to the use of one-step (eg CIP, CIL process) gold extraction process can significantly reduce the time immersion gold.


Thiourea gold extraction is a non-toxic gold extraction new technology, China has used this method to handle the re-election of gold concentrate and flotation gold concentrate. However, this process still exists the problem of high cost.


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