Tin ore is one of the important strategic mineral resources, tin and tin alloys have been widely used in modern national defense, industry, cutting-edge science and technology, and also in our daily life.

The development of tine ore beneficiation

The beneficiation method of tin ore is determined by its own characteristics. Because the density of cassiterite is higher than that of co-existing minerals, the traditional beneficiation process of tin ore is gravity beneficiation. 

With the passage of time, the granularity of cassiterite in the selected ore has been continuously reduced, so that the cassiterite flotation process has emerged. 

In addition, since there are often various iron oxide minerals in tin minerals, such as magnetite, hematite and limonite, these minerals cannot be well separated from cassiterite by flotation and gravity separation. So, the magnetic separation operation has then been introduced in the tin ore beneficiation process.

At present, the common tin ore beneficiation processes mainly include gravity separation, flotation, and magnetic separation, that is, the raw ore is washed and deslimed, crushed and screened, pre-selected, and then passed through gravity separation equipment, flotation machine, magnetic separation.

Usually, there is often one or more equipment being used for processing and beneficiation tin ores, thus the finally tin concentrate can get an ideal grade and high recovery rate.

Below are the three beneficiaiton flow used in tin ore beneficiation.

Tin ore gravity Separation:

In fact, most of the tin concentrates come from cassiterite deposits. The density of cassiterite is higher than that of the symbiotic minerals. So the gravity separation method can use the density difference between the cassiterite and the symbiotic minerals to separate the tin concentrates. 

Actually, gravity separation is one of the most important beneficiation processes for tin ore at present, and it is often used to separate tin sand ores.

The gravity separation method is generally used for sand tin ore. The process of gravity separation of tin sand ore usually adopts multi-stage grinding and multi-stage separation process. 

Those processing can make tin ores dissociation and get recovered in the early stage processing and also remove some tailing to avoid uneven embedding. The cassiterite of the cloth caused excessive shattering. 

In addition, since cassiterite will produce slime in the crushing stage, classification desliming is an important preparatory operation before cassiterite gravity bneficiation. It can also control the size selection while removing the interference of ore slime. 

Generally, ore washing machines and cross-flow belt chutes are used. , small diameter cyclone and other equipment such as cassiterite desliming equipment. The commonly used gravity separation equipment for tin ore mainly includes mineral jig and shaking table.

Tin ore flotation:

The tin ore flotation process is usually used for processing tin minerals with a size less than 19 μm, the gravity separation method cannot handle those fine-grained tin ore at this size. And there is one thing to point out that although the flotation method can effectively recover tin concentrate, there are also have some shortages, such as cause large surface area of ore particles and large consumption of chemicals.

In order to improve the flotation effect and improve the recovery rate of tin concentrate, two methods can be considered,

One is to pretreat fine-grained tin minerals before flotation; the other is to use an effective combination of flotation reagents and equipment.

Common pretreatment methods include intensive slurry stirring, large-diameter hydrocyclone classification, small-diameter hydrocyclone desliming, lowering the lower limit of classification particle size and the lower limit of desliming particle size.

Common collectors in cassiterite flotation include fatty acid collectors, alkyl sulfosuccinic acid collectors, phosphonic acid, arsine acid, etc. Water glass is often used together with sodium carbonate and sodium hydroxide as a pH adjuster for tin ore flotation. Among them, water glass has inhibitory effect on cassiterite, calcite, scheelite, quartz, feldspar and other minerals, but it has an inhibitory effect on various minerals. The inhibitory effect of the quasi-minerals varies according to the dosage. Generally, the concentrate grade and enrichment obtained when the pH is 10 is better. Sodium hexametaphosphate is used to inhibit calcite, limonite and other minerals in cassiterite flotation, and can be used with oleic acid. Sodium fluorosilicate is a commonly used medium modifier in the flotation of cassiterite fine mud. When used in combination with sodium alkyl sulfate and styrene phosphonic acid, it can expand the flotation area, which is beneficial to the floating of cassiterite. It can also be used as an inhibitor of gangue minerals to improve the concentrate grade. Carboxymethylcellulose is also a commonly used calcite inhibitor. In addition to the above regulators, common regulators for cassiterite flotation include: hydrogen sulfide, sodium sulfide, amine naphthol sulfur, low molecular weight oxalic acid, citric acid, lactic acid, tartaric acid, etc.

The tin ore beneficiation equipment used in this process includes various types of suction mechanical stirring flotation machines (SF type flotation machine, BF type flotation machine, JJF type flotation machine) and pneumatic mechanical stirring flotation machine (KYF type flotation machine). Flotation machine, XCF flotation machine).

Tin Ore Magnetic Separation

Tin ore of a single type is actually rare, and the common ones contain iron oxide minerals (magnetite, hematite, limonite, etc.), tungsten ore and other symbiotic minerals. For this kind of complex tin ore flotation and gravity separation, it is difficult to achieve a good separation effect.

Therefore, magnetic separation is often used in the washing process to realize the separation of tin and iron. The magnetic separation of tin ore is mainly wet strong magnetic separation, which is used for the raw ore, secondary concentrate and concentrate before entering the gravity separation operation, while the dry magnetic separation process is often used to separate tungsten and tin minerals. Commonly used magnetic separation equipment includes wet magnetic separator and dry magnetic separator.

If the associated mineral is iron oxide, the magnetic separation method can be used to realize the separation of tin and iron. Wet strong magnetic separation is the main method, which is used before the original ore, secondary concentrate and concentrate enter the gravity separation operation;

If the associated mineral is tungsten ore, the dry magnetic separation process is used. The main mineral density of tungsten and tin ore is relatively high, and wolframite, scheelite and cassiterite are generally accumulated in the coarse concentrate. The wolframite can be separated from cassiterite and scheelite through the operation of a dry strong magnetic separator, and then the cassiterite and scheelite can be separated by electric separation.

Practices Of Tin Beneficiation

Gravity beneficiation practice of tin ore

One of our customers, because the cassiterite in its mine has a certain difference in the inlaid characteristics of cassiterite in the size larger than 5mm and smaller than 5mm, so the coarse and fine classification is based on 5mm. Coarse sand of +5mm is jigged twice after the rod mill, and the tailings of the first jig are swept with a shaker to obtain a coarse concentrate with a tin grade of 8% to 9%, which is sent to the second stage mill. The fine sand of -5mm is classified with a Φ600mm cyclone, the sand is sorted by two jigs, and its overflow is classified with a Φ400mm cyclone and sorted with a shaking table.

Gravity beneficiation with flotation beneficiation practice case for tin ore

For example, Yunxi companies have been used the flotation-gravity beneficiation process in the sulfide ore workshop of Datun Concentrator for more than 30 years. Flotation: one roughing, two sweeping, one refining; copper-sulfur separation and grinding to 0.074mm, accounting for 95%, one-coarse, two-sweeping and three-refining, to produce copper concentrate and sulfur concentrate; mixed flotation tailings are re-selected for sulfide and then re-selected. After the first and second stage bed selection; once rewashing; mud selection; tin coarse concentrate desulfurization flotation, tin concentrate and rich medium ore are produced.

In addition, one of our tin beneficiation plant customers has a beneficiation process that firstly crushes the raw ore to -20mm, then sieves it into two grades of 20-4mm and 4-0mm, and 20-4mm enters the heavy medium cyclone for pre-selection. After a stage of rod grinding, the heavy products of the heavy medium cyclone are pre-selected by jigging, and the jig tailings are screened with a 2mm vibrating screen to remove +2mm as waste tailings, and -2mm enter the shaking table for sorting. Jigging and shaking table concentrates and medium ore are divided into rich and poor systems according to their grades, and they are respectively reground and mixed flotation. The mixed flotation tailings are shaken to produce qualified tin concentrates; the mixed flotation concentrates are then finely ground for lead-zinc separation and flotation, and lead-antimony concentrates and zinc concentrates are respectively produced. Gravity sludge enters into Φ300mm cyclone, and the overflow goes through Φ125mm and Φ75mm hydrocyclones to remove fine mud. The sediment is concentrated, flotation desulfurization and then cassiterite flotation.

United beneficiation processing for tin ore

There are one of our customer use all those three beneficiation method on their tin ore processing flow.

Their tin ore contain a large and extremely rich ore body of cassiterite polymetallic sulfide ore in a certain place. The ore contains high grades of tin, lead, antimony and zinc, and contains associated elements and rare and precious metal elements that can be comprehensively recovered from sulfur, arsenic, cadmium, indium, silver, and gold. The ore has many kinds of minerals, complex components, and difficult beneficiation. After scientific and technological research, the two major principles of magnetic separation –> flotation –> gravity separation and magnetic separation –> gravity separation –> flotation –> gravity separation were used to expand the test, and achieved good results. Select indicator.

Magnetic separation –> flotation –> gravity separation process is applied in the concentrator, and the sulfide ore flotation adopts a two-stage mixed flotation separation process to obtain tin, lead, antimony and zinc recovery rates of 83.72%, 82.16%, 73.89% and 80.50%. After transformation, the design process is magnetic separation–>flotation–>gravity separation process, and the flotation of sulfide ore adopts the priority mixing and flotation separation process, and the recovery rates of tin, lead, antimony and zinc are 78.11% and 85.59% respectively. , 82.63% and 81.65%.

In the actual beneficiation process, the selection of tin ore beneficiation process and equipment is often determined according to various factors such as the nature of tin ore, dressing plant conditions, and investment budget. If you want to separate tin ore more economically and environmentally, you should first carry out a beneficiation test, comprehensively analyze the properties of the ore, and obtain a scientific beneficiation test report, so as to judge the type of tin ore beneficiation process and specific tin ore beneficiation equipment. with model numbers to achieve the ideal ROI.