Common pyrite mainly includes pyrite, white iron ore, pyrrhotite, etc., which widely exists in various types of deposits, among which pyrite is very common. China is rich in pyrite resources, mostly of medium and low grade, and rich ore (grade over 35%) only accounts for about 4% of the total reserves. Pyrite is the main sulfur resource in China, and China accounts for about half of the sulfuric acid produced from pyrite in the world, which promotes the development of pyrite beneficiation technology.
At present, sulfur is relatively mature, and flotation is the main method, supplemented by gravity separation. According to the different properties of ore, single gravity separation and flotation separation process can be adopted, or combined gravity separation and flotation process can be adopted for recovery.
I. single gravity separation process and equipment for pyrite
When choosing pyrite beneficiation process, due to the limited recovery value of pyrite, special attention should be paid to the economic rationality of pyrite beneficiation process. For pyrite with simple ore properties and coarse disseminated grain size, a single gravity separation process can be considered. Common gravity separation equipment, such as shaker, jig and spiral chute, can effectively recover pyrite.
Taking pyrite mine as an example, under the condition of no grinding, the gravity separation process of coarse jigging-fine spiral chute was adopted to recover pyrite in this mine, and high-grade pyrite concentrate could be obtained through jigging and spiral chute.
The advantages of single gravity separation process are simple process, simple equipment maintenance, low energy consumption and low beneficiation cost, but the disadvantage is low recovery rate of pyrite.
2. pyrite single flotation process and equipment
For single pyrite, xanthates can be used as collectors, such as ethyl xanthate, butyl xanthate and isobutyl xanthate, which can effectively recover pyrite. In some cases, pyrite is oxidized to a certain extent, and its floatability is weakened, so it is necessary to add activators such as sulfuric acid and oxalic acid to improve the recovery rate of flotation.
When pyrite is associated with other valuable metal sulfides, such as chalcopyrite, galena, sphalerite, etc., pyrite needs to be removed as an impurity in most cases, so it is necessary to suppress pyrite in the flotation process to improve the grade of the target mineral concentrate. Lime, sodium sulfide, sodium humate and other inhibitors are generally used to inhibit pyrite in alkaline flotation environment.
However, when pyrite is associated with other valuable metal sulfides and pyrite has certain recycling value, it is necessary to consider the activation of the suppressed pyrite. Sulfuric acid, copper sulfate and lead nitrate can be used as activators of pyrite, and then pyrite can be recovered by flotation. In production practice, when two or more activators are used in combination to activate ferric sulfate, better flotation results can often be obtained. There are many suitable flotation machines for pyrite separation, such as XCF flotation machine, KYF flotation machine, SF flotation machine, etc. As for the selection of flotation equipment, the separation should be carried out according to the actual situation of ore.
3. pyrite gravity separation-flotation combined process and equipment
The combined gravity separation-flotation process is suitable for pyrite with uneven mineral disseminated grain size or fragile and easy to grind. The combined gravity separation-flotation process is generally coarse grinding and classification of raw ore, and proper gravity separation equipment is adopted to obtain a part of pyrite concentrate, and then the gravity separation middlings and tailings are floated or reground and reselected by proper flotation process.
In a word, the selection of pyrite beneficiation process depends primarily on the nature of the ore. Single gravity separation method is suitable for treating coarse-grained disseminated pyrite; Single flotation method generally deals with hydrothermal, late contact metasomatic and metamorphic pyrite with fine disseminated particle size, and at the same time, attention should be paid to the selection and use of flotation reagents; The combined gravity separation-flotation process is suitable for treating pyrite with uneven disseminated grain size. Different minerals have great differences in properties, so it is necessary to determine the appropriate beneficiation process and equip with equipment to ensure the beneficiation effect in actual production.
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