The mylonite type gold deposit is an important type of gold deposit, which has the characteristics of lateral arrangement, fine-grained, and large reserves. A certain mylonite type sulfur poor gold deposit, with ore minerals mainly including natural gold, pyrite, arsenopyrite, and magnetite; The main gangue minerals are sericite and quartz, carbonaceous and carbonate in metasomatic mylonites, and thermally metamorphosed biotite.
The initial construction of the gold ore beneficiation plant adopted a beneficiation process flow of "water jacket gold concentrator rough selection chute sweeping selection shaking bed selection". Although the recovery rate can also meet the standard, the beneficiation process is lengthy and the recovery rate is relatively low. The researchers simplified the beneficiation process based on the properties of the ore and achieved good results.
The main recyclable valuable elements in the ore are gold and silver, with a gold grade of 1.57g/t and a silver grade of 13.9g/t. Gold in ores mainly exists in exposed and semi exposed states, with a occupancy rate of 69.43%. The gold content in sulfides is relatively low, with a occupancy rate of only 5.09%, hence it is called a sulfur poor gold mine.
The commonly used separation methods for gold mines include flotation, gravity separation, leaching, and combined processes. In recent years, with the improvement of environmental awareness, the requirements for environmental protection in the mineral processing industry have also been increasing year by year. The advantages of gravity separation lie in low pollution and environmental protection. Therefore, the gravity separation method has received increasing attention and widespread application in gold ore beneficiation. Many gold beneficiation plants have transformed the production process of single flotation active cyanide method into a combined process of gravity separation flotation active gravity separation leaching.
The process of mineral processing experiment carried out single flotation test, Nielsen gravity separation test, and gravity flotation combined test on the ore.
(1) Single flotation test
Under the conditions of a grinding fineness of -0.074mm accounting for 70%, lime as an adjusting agent, butyl xanthate as a collector, and No. 2 oil as a foaming agent, a single flotation process was adopted. After one rough selection, one sweep selection, and two selections, a gold concentrate grade of 63.90g/t was obtained with a recovery rate of 80.19%.
(2) Nielsen reselection test
Under the condition of a grinding fineness of -0.074mm accounting for 70%, using the Nielsen gravity separation process, a heavy sand gold grade of 364.62g/t can be obtained with a recovery rate of 83.41%.
(3) Heavy floating joint test
Under the condition of a grinding fineness of -0.074mm accounting for 70%, using a heavy flotation combined process can obtain a heavy sand gold grade of 345.20g/t; The re selected tailings can obtain a flotation gold concentrate grade of 34.52g/t through one rough selection, one sweeping selection, and two selections, with a comprehensive recovery rate of 83.95%.
Based on the results of three experiments, the short process gravity separation process using Nielsen rough selection, sweeping and shaking bed concentrate is determined.
(1) By setting up a coarse screen, control the appropriate Nielsen coarse selection feeding particle size. After the transformation, the sedimentation problem of coarse gold inside the grinding circuit has been reduced, achieving early collection and improving sorting efficiency.
(2) By installing an overflow pipe under the funnel of the linear vibrating screen, it is ensured that the feed slurry can be connected to the feeding pump pool of the linear vibrating screen during the discharge of Nielsen concentrate, preventing the upper part of Nielsen equipment from overflowing and reducing slurry loss.
(3) By setting up Nielsen sweeping in the overflow slurry of the hydrocyclone, gold metal can be fully recovered, further improving the gold recovery rate.
(4) By retaining the shaking table for further selection of Nielsen rough and sweep concentrate, the shaking table concentrate can be directly used as the final high-grade concentrate in the smelting process. The ore and tailings in the shaking table can be stored for sale as low-grade concentrate, achieving the classification and quality utilization of concentrate products.
