Flotation is widely used in gold processing. In China, 80% rock gold is processed by flotation. Flotation process maximizes the enrichment of gold into sulfide minerals. The tailings can be directly discharged. Flotation in gold mine has low beneficiation cost.
Gold mineral flotation normally adopts one stage grinding-flotation process, but stages grinding and flotation for ore with uneven distribution.
For the gold wrapped in sulfide minerals, sulfide ore reaches monomer dissociation; but for the gold with gangue, grinding fineness should reach gold monomer dissociation. Grinding fineness of minerals is determined by test.
Flotation for large density and coarse particle needs thick pulp, whereas for small density and fine particle, need dilute pulp.
In addition to the grinding fineness, process conditions of gold flotation also includes slurry concentration, reagent dosage, aeration quantity and flotation time.
Taking a gold mine in Yunnan as an example, the scale of the processing plant is 300t/d. The main mineral in the ore is pyrite. The grain size of gold is fine and it is closely related to metal sulfide minerals. This plant adopted the flotation process---one roughing, two cleaning and two scavenging. But due to surface oxidation of arsenic antimony mineral, it adsorbed amount of flotation reagents, and the flotation effect was poor. So The plant owner authorized Xinhai to reform the process. Xinhai replaced cyclone tailings with stages grinding & flotation and flotation tailings in accordance with existing problems in production, and Xinhai also changed the number of machine and reagents rules. Finally, this plant obtained excellent indexes. The indexes comparison are as following:
|Products Name||Gold Concentrate Grade/（g/t）||Gold Recovery Rate/%|
|Before Reformation||Gold Concentrate||34.38||81.80|
|After Reformation||Gold Concentrate||33.35||90.62|
The original gold ore flotation process is changed to a stage grinding and flotation process, which is easier to operate, and can achieve early and fast harvest of useful minerals in ores with higher impurities; adjust the structure of the flotation machine to improve the separation environment and the mineralization effect of the flotation slurry and ensures the stability of the index and the smooth flow of the process.
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