Process Inspection And Process Optimization Test Research Of Beiya Gold Concentrator

My master's thesis was focused on the low leaching rate of Beiya iron-gold-silver ore in Yunnan province.The major valuable metals in the mine were gold and iron.The gold grade in this ore was 1.57g/t,which was mainly consisted of natural gold and rest of the gold existed in silicate minerals and iron minerals.The iron grade in this ore was 25.98%,which was mainly in the phase of hematite and limonite,while a small amount of the iron was in the form of sulfide.The silver grade in this ore was 41.2g/t,which was mainly existed in lead minerals and in the form of free silver.The copper grade in this ore was 0.37%,which mainly existed in the presence of copper oxide and rest of the copper was in the form of copper sulfide minerals.The major gangue were quartz and dolomite.The cyanidation leaching rates of Au and Ag were relatively low in this 2000 t/d gold ore processing plant.According to the investigation results of leaching process,the reasons for the low recoveries of Au and Ag in cyanidation leaching were as the following:1.Only 74.5% of the particles had a particle size less than 0.043 mm in the slurry for cyanidation leaching,due to the low classification efficiency of the cyclone,which was only 39.95%.2.Both the cyanide concentration and p H value in the ore pulp were low in the cyanidation leaching process.The leaching rate would be even worse if the copper grade in the ore increased.3.Insufficient aeration or even aeration interruption would occurred due to the aging of the in the stirred aeration tank,when the leaching time and the pulp concentration were increased.To improve the leaching recoveries of Au and Ag,laboratory tests on optimization of process with various grinding fineness,dosage of lime,dosage of sodium cyanide and different type of leaching reagents were conducted.It was found that increasing the grinding fineness to 85% of the particles had a particle size less than 0.043 mm would significantly improve the leaching rates of Au and Ag.Meanwhile,the optimized leaching p H value was between 11 and 12.Besides,improving the dissolved oxygen concentration was benefit for the leaching rates.Based on the laboratory test results,a series of pilot tests were carried out with different grinding fineness,cyanide ion concentration,leaching time(which was related to the leaching pulp concentration),and grade of cupper in ore.As a result,the leaching rates Au and Ag were significantly increased to 90.91% and 37.8%,respectively,with a feed ore which only contained 1.65 g/t Au and 45.3 g/t Ag.A preliminarily estimation showed that the optimized processing will improve the production of this 2000 t/d plant with 482 kg Au and 1206 kg Ag each year,which realized the estimated profit is 101079.7 thousand yuan,would be a great economic benefits.