Flotation is a commonly used process in gold concentrators. It is mainly suitable for sulfide gold bearing quartz vein ore with good floatability, processing polymetallic gold bearing sulfide ore and graphite bearing gold ore. In the production process, the general gold ore flotation process mainly includes crushing and grinding operations, separation operations and dehydration operations. In this paper, we will start from different operation stages to understand the equipment required for gold ore flotation process.
Whether gold can be effectively recovered mainly depends on the mineral properties and particle size distribution of gold. Therefore, crushing and grinding are very important. The raw ore enters the crusher for crushing and then enters the vibrating screen for screening. The upper product is crushed and the broken product is screened. The products under the screen pass through the primary grinding. The grinding and classification equipment form a closed circuit grinding. After classification, the grinding products enter the second stage ball mill for regrinding, and then form a closed circuit grinding with the cyclone. For gold sulfide with good floatability, grind to - 75 μ M60~80% can achieve monomer dissociation.
In the crushing operation, generally, small and medium-sized gold concentrators use two-stage one closed circuit ore crushing, while large gold concentrators use three-stage one closed circuit ore crushing process. Jaw crusher is used for coarse crushing, cone crusher for medium crushing or fine crushing, ball mill equipment is used in grinding stage, grid type ball mill is used for primary grinding, overflow type ball mill is used for secondary grinding.
The flotation separation of gold is mainly based on the different physical and chemical properties of mineral particle surface and the different floatability of minerals. The commonly used flotation processes mainly include single flotation, flotation gravity separation, flotation concentrate cyanidation, flotation roasting cyanidation, etc.
Single flotation is to first float gold into copper and sulfur concentrates, and then extract gold from these concentrates. Therefore, it is an economical and reasonable process flow for gold ores containing nonferrous metals in raw ores. Single flotation can not only enrich gold into sulfide minerals as much as possible, but also realize comprehensive utilization of multi metals. However, the final gold product cannot be obtained, and the combined process flow is often formed with other mineral processing methods.
This technological process is to obtain flotation concentrate from raw ore through flotation separation, and the sulfide part in flotation tailings often exists in the form of intergrowth with gangue. In addition to being wrapped in sulfide by submicroscopic fine particles, gold often exists as coarse and fine single gold. Coarse sulfide, gangue intergrowth and coarse natural gold in tailings are difficult to recover by flotation, so part of gold can be recovered better by gravity separation.
In this process, xanthates are generally used as collectors, terpineol oil as foaming agent, and weakly alkaline pulp is floated in a flotation machine to obtain gold concentrate. Then the flotation concentrate is subject to cyanide leaching, the gold is dissolved by cyanide, the complex enters the solution, and the gold mud is obtained by replacing it with zinc powder. Finally, the gold mud is pyrometallurgical to obtain pure gold.
For the flotation concentrate containing arsenic and high sulfur, after the flotation of cyanide tailings, sulfur, iron, arsenic and other impurities are enriched in the concentrate to become a refractory high sulfur and high arsenic concentrate. If it is impossible to directly cyanide leach, the flotation gold concentrate can be oxidized and roasted first to remove arsenic and sulfur. In this way, the calcine structure after roasting is loose, which is more conducive to the leaching of gold and silver.
In the sorting operation, the commonly used flotation machines are mainly mechanical stirring flotation machines (SF, JJF, BF), aerated stirring flotation machines (XCF, KYF) and flotation columns. Among them, SF type, JJF type and XCF type are suitable for roughing and scavenging operations, KYF type and BF type are suitable for roughing and concentration operations, and flotation column is mainly suitable for gold minerals with fine particle size and small density, which are less used in rock gold mines.
Generally, gold mine dewatering includes concentrate dewatering and tailings dewatering. For concentrate dewatering, it is necessary to judge whether dewatering is required according to the process used for concentrate operation, and the process of concentration+filtration dewatering is mostly adopted. Tailings dewatering is customized according to the properties of tailings slurry.
Dehydration equipment commonly used in dehydration operation includes thickener, filter press, cyclone, etc. The thickener can be used for primary dehydration of concentrate and tailings, as well as concentration or leaching washing before leaching in cyanidation plant. Cyclones and filter presses are mainly used for tailings dewatering.
This is the introduction of gold ore flotation process and related equipment. However, not all gold ores are suitable for flotation process, and gold resources are very precious. In order to separate ores more reasonably, the beneficiation process is very important. If you want to select gold from gold ore more economically and environmentally, you should first carry out experimental analysis on the ore, customize the beneficiation process according to the situation through scientific and reasonable test reports, so as to achieve an ideal rate of return on investment.
