Pretreatment with sulfide ores containing gold pressure oxidation approach to enable the oxidation of sulfide ore, and out of the heavy metal oxide dissociation and removal of sulfate, followed by cyanide leaching gold extraction method is referred to as a pressurized oxidation. 2FeS 2 +7O 2 +2H 2 O → 2FeSO 4 +2H 2 SO 4 4FeSO 4 +2H 2 SO 4 +O 2 → 2Fe 2 ( SO 4 ) 3 +2H 2 O MeS+2O 2 → MeSO 4 By oxidation, gold is dissociated from the inclusions of the sulfide. Parameter name Wide range of Narrow range Temperature (°C) 14 0～ 200 160 to 180 Pressure ( kPa ) 966 ～ 2069 1241 ~ 1319 Residence time (hours) 1 to 4 1.5 to 2 Slurry concentration ( % ) 40 to 50 40 to 45 Final acidity ( g/LH 2 SO 4 ) 5 to 20 7 to 15 Final electromotive force ( mV ) 420 420 The temperature used in the autoclave should be higher than the melting point of sulfur (118 ° C), more preferably 170 ° C, in order to fully oxidize sulfides such as pyrite, reducing the formation of elemental sulfur. Elemental sulfur is undesirable because elemental sulfur can cause gold to be encapsulated, as well as generate unreacted sulfides during pressurized oxidation, and increase reagent consumption during subsequent cyanidation. Ningbo Yejin Supply Chain Management Co.,Ltd , https://www.car-parts-accessories.com
The process is that the finely ground pulp ore is sent to a pressurized container for oxidation pretreatment. The commonly used pressurized vessel is a complex multi-chamber autoclave with agitation. Oxygen is added to each chamber. Under acidic conditions, the sulfide in the ore is destroyed to produce sulfuric acid, ferric sulfate, ferrous sulfate and other ruthenium metal sulfate. a mixture of salts:
When oxygen is used as the oxidant, the operating parameters of the autoclave are shown in the table below.
The purpose of using H 2 SO 4 is mainly to prevent a large amount of precipitation of the iron compound FeOHSO 4 or FeAsO 4 because such precipitation can passivate the dissociation of gold, thereby preventing the dissolution of gold.
The autoclave is discharged through the flash tank, and the oxidized slurry is fed into the second-stage washing and concentrating system. A high wash volume ratio is employed to effectively remove acid and dissolved base metals from the feed to the gold recovery system. After the above treatment, the cyanide leaching speed of gold is fast and the leaching rate is high.
Recent studies have shown that the use of thiourea to directly extract gold from pressurized oxidized acidic pulp can reduce multiple washing and neutralization operations and reduce processing costs.
Pressurized oxidation pretreatment is an effective method.