Quartz is generally associated with low to moderate temperature hydrothermal alteration, at which temperatures gold can easily be enriched to industrial levels. This is how quartz vein gold deposits form.
Quartz vein gold ore is generally grayish-yellow-white in appearance, and its internal structure is mostly medium-fine grained with a disseminated structure. The ore minerals are mainly chalcopyrite, pyrite, sphalerite, and natural gold, and the gangue minerals are mainly quartz, calcite, feldspar, etc. Chalcopyrite and pyrite are mostly distributed in patches in quartz veins.
A typical quartz vein gold ore was selected as the sample ore. The main useful mineral is gold, followed by a small amount of silver and pyrite, and the main gangue mineral is quartz.
The main valuable element recovered in the ore is gold, with a grade of 0.9 g/ton. The physical phase analysis results show that the quartz vein gold is mainly bare gold. The content of other metallic minerals is small, mainly pyrite, with a grade of 0.1%. Gangue minerals mainly include quartz, sericite, and sodalite.
In the original quartz vein gold ore, the gold mineral is mainly single gold, part of which forms fine veins of arsenopyrite and is wrapped by pyrite. A small amount is associated with gangue and limonite. -2mm raw ore screening analysis results show that most of the gold in the quartz vein gold ore is distributed in coarse-grained grades, with a +74um grade metal distribution rate of 87.87% and a -37um grade metal distribution rate of 87.87%.
According to the properties of quartz vein gold ore, three gold separation tests were conducted:
First, flotation trials are conducted to determine the appropriate flotation chemistry, grinding size, and flotation time. On this basis, the first-level rough separation, second-level selection, and second-level scavenging and flotation processes are adopted.
The final gold concentrate yield was 0.93%, the grade reached 96.8g/t, and the recovery rate was 95.77%. The gold beneficiation effect is good, but there is a phenomenon of coarse-grained gold sinking in the flotation tank, which has a certain impact on the gold concentrate indicators.
The gravity separation process is a traditional method for the pollution-free recovery of granular gold. However, it has shortcomings such as low enrichment ratio and small processing capacity. In the gold separation test of quartz vein gold ore, shaking table separation was first carried out, and then the gold concentrate was flotated using the flotation process.
Finally, the comprehensive grade of the concentrate obtained through the combined gravity method and flotation method was 133.77 g/t, the recovery rate was 91.32%, and the tailings loss rate was 6.09%. The gold beneficiation test results show that the combined process of shaking table separation and flotation can recover gold well.
First, conduct the grinding fineness test and Nelson gravity multiple test to determine the optimal grinding fineness and optimal gravity multiple respectively. After determining the two major factors, the Nelson gold separation combined process, shaking table separation and flotation process trials were started.
It can be seen from the quartz vein gold beneficiation test that the three processes of single flotation, Nelson, shaker separation and flotation combined process, and shaker separation and flotation combination can better recover gold in raw ore. However, these three processes each have their own characteristics.
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