General beneficiation method of tin ore - gravity separation

The density of cassiterite (SnO2) is 6800~7000 kg/m3, and it is often symbiotic with gangue minerals (such as quartz, feldspar, muscovite, etc.) with a density of about 3000 kg/m3.

Gravity beneficiation is the basic method of cassiterite separation. More than 85% of the world's tin concentrates come from gravity beneficiation operations. Gravity beneficiation can be used as cassiterite pre-enrichment means, and can also directly produce qualified cassiterite concentrate. In the Bronze Age, people began to use gravity beneficiation to enrich tin minerals. Since the 1960s, tin beneficiation has developed from a single gravity beneficiation to a combined process consisting of gravity beneficiation, flotation, magnetic separation, and electrical separation.

Grading desliming is a necessary preparation for the cassiterite gravity beneficiation process. The desliming equipment used mainly includes water guns, various washing machines, Bartley-Maudsley turning beds, cross-flow belt chutes and hydrocyclones. Medium concentrators and jigs mostly use dry coarse-grained and medium-grained cassiterite for pre-selection; screw concentrators use dry to effectively recover cassiterite with a particle size of 0.074~1 mm. The enrichment ratio of the shaker separation is high, which can not only select high-grade cassiterite concentrate, but also throw out the final tailings, which is the main equipment of the tin processing plant. Centrifugal concentrators are used to sort tin slime with a dry size of 0.037 mm.

Tin ore is divided into sand tin ore and vein tin ore. Sand tin ore is the main mining object, accounting for about 75% of the total mining volume. Sand tin ore generally adopts the gravity beneficiation process of stage grinding, stage separation, mud sand separation, and rich and poor separation. Vein tin ore has cassiterite-oxide mineral type, cassiterite-quartz type and cassiterite-sulfide mineral type.

The cassiterite-oxide mineral type mainly adopts a single gravity beneficiation process, mainly using a shaking table, and multi-grinding and multi-separation operations. Cassiterite-quartz type and cassiterite-sulfide mineral type are generally pre-selected by rich separation or heavy media separation, rough separation by jig and shaker, and finally by flotation, gravity beneficiation, magnetic separation, and electric separation. The process is selected to produce the final concentrate.

After the raw ore is ground to less than 1.5 mm in one stage, the middle 500 mm and middle 250 m hydrocyclones are used for two-stage classification, and the particles larger than 74 microns and 37~74 microns are still sorted and classified in a flat field shaker. After mixing with the secondary ore, Baiping uses a @125 high-meter hydraulic flow applicator to carry out late sludge, and discards the fine 19-micron or 1000-micron fine ore sludge with a very low tin content. Centrifugal concentrator, belt chute, shaker for sand settling.