Tin Ore Gravity Separation: Influencing Factors, Advantages & Disadvantages

Tin ore, as a key strategic metal resource, plays an indispensable role in electronics, metallurgy, chemical industry, and other fields. Among the many beneficiation methods for tin ore,  gravity separation has become one of the most commonly used means with its unique advantages, especially good at dealing with coarse-grained embedded tin ore. The following is an introduction to the influencing factors as well as the advantages and disadvantages of the tin ore gravity separation.

 

 

Factors Affecting The Effect Of Tin Ore Gravity Separation

The effect of tin ore gravity separation is affected by multiple factors, mainly involving the characteristics of the ore itself, the properties of the separation medium, the type of equipment, and operating conditions. The following is a detailed analysis of the key influencing factors and optimization directions:

1. Ore properties

Ore properties such as the embedded particle size, density, shape of cassiterite, and the composition of gangue minerals, etc.

Mineral density difference

The density of cassiterite (6.4~7.1 g/cm³) is significantly higher than that of gangue minerals (such as quartz and silicate minerals). The greater the density difference, the higher the separation efficiency. When the density difference is less than 0.5, the gravity separation effect is significantly reduced, and other processes (such as flotation) are required to assist in the separation. If the ore contains minerals with higher density such as magnetite and hematite, they need to be separated in advance by magnetic separation or flotation to avoid interfering with the gravity separation stratification.

 

Particle size distribution and shape

• Effective particle size range: Gravity separation has the best separation effect on medium and coarse particles (0.074~2mm), and fine particles (<0.037mm) are easy to lose due to slow sedimentation. Centrifugal concentrators and other technologies can extend the separation limit to 10μm, but the recovery rate is still limited.
• Shape influence: Flake or flat particles have slow sedimentation speed and are easily mixed with light minerals. Grading pretreatment is required to reduce shape interference

    

Ore Mud Content

Ores with high mud content need to be pre-washed and de-mudded to avoid mud-encapsulating mineral particles or clogging the equipment. For example, the use of a trommel scrubber to treat sticky mud improves the efficiency of subsequent reclassification.

 

2. Sorting media properties

Media properties, such as density, viscosity, and flow rate characteristics of the media.

Media type and density

• Aqueous media: commonly used and low cost, but the density is fixed (1g/cm³) and the sorting accuracy is limited. Heavy media (such as heavy liquid or heavy suspension) can improve the sorting accuracy (density difference of 0.02), but the cost is high.
• Air media: used in water-scarce areas (wind power beneficiation), but the sorting efficiency is low, only for specific scenarios

     

Media flow state

Water flow speed and turbulence degree affect particle stratification. For example, the pulsation of the water flow in a jigger needs to be matched to the size of the ore: coarse-grained ores require large strokes and low impulses, while fine-grained ores require the opposite.

 

 

3. Equipment Types and Operating Parameters

Equipment Selection

• Jig separator: suitable for coarse-grained ore, optimize the bed looseness by adjusting the stroke, the number of strokes, and the amount of water replenishment under the screen.
• Shaking table: suitable for fine-grained ore, through the adjustment of lateral slope, washing water volume to achieve “large slope and small water” (roughing) or “small slope and large water” (selection).
• Spiral chute and centrifuge: for processing medium and fine-grained ore, it is necessary to control the feeding concentration (10%~35%) and washing water volume to avoid overloading or incomplete sorting.

 

 

Optimization of operating parameters

• Feed concentration: too high concentration (>25%) will reduce the efficiency of stratification, and need to be controlled by grading or dilution.
• Water flow and bubble matching: in the centrifugal concentrator, the bubble size needs to match with the mineral particle size (e.g. -10μm particles need 45~59μm bubbles), to improve the probability of collision.

 

 

Advantages & Disadvantages of Tin Ore gravity separation

Tin ore gravity separation is a separating method based on the difference in mineral density, its advantages and disadvantages need to be combined with the characteristics of the ore, process, and equipment selection comprehensive assessment.

 

Advantages of tin ore gravity separation

 

Simple operation and low cost

The gravity separation method does not need a complex pharmaceutical system, mainly relying on physical separation (such as water flow, and gravity field), equipment investment and operating costs are significantly lower than flotation or magnetic separation. For example, jig separators, spiral chutes, and other equipment with simple structures and low energy consumption are suitable for small and medium-sized mines.

 

Outstanding environmental protection

The gravity separation process does not involve chemicals, which avoids the discharge of harmful substances in wastewater and meets the development requirements of green mines. It is especially suitable for areas with strict requirements for environmental protection.

 

High efficiency of coarse grain sorting

For medium and coarse-grained cassiterite (0.074~2mm), the gravity separation method can effectively utilize the density difference to achieve high-efficiency sorting. For example, the recovery rate of jigger can reach more than 70% when treating coarse-grained cassiterite, which is especially suitable for cassiterite-sulfide type or cassiterite-silica type ores.

 

Strong adaptability

It can process many types of tin ores, including hard cassiterite, wolframite, and other minerals with significant density differences. The shaking table can also be adapted to different grain sizes by adjusting the lateral slope and water flow rate.

 

Disadvantages of tin ore gravity separation

 

Poor separation of fine and micro-fine grains

Gravity separation is inefficient in sorting fine (<0.037mm) and micro-fine (<0.01mm) cassiterite, and is prone to metal loss due to insufficient settling velocity. For example, the recovery of -0.02mm cassiterite from a shaker may be less than 30%, requiring the assistance of a flotation or centrifuge.

 

High equipment wear and maintenance costs

The gravity separation equipment (e.g. jigger screen, inner wall of spiral chute) is easy to wear under the impact of high hardness ore, and wear-resistant parts (e.g. high chrome cast iron) need to be replaced regularly, which increases the maintenance cost.

 

Strict pretreatment requirements

• High mud content: Pre-washing is required to remove the mud, otherwise the mud wrapped around the mineral particles will interfere with the sorting. For example, viscous soil needs to be processed through the cylinder washing machine.
• Particle size control:multi-stage crushing and screening (e.g. four-roll crusher to avoid over-crushing) is required, otherwise the mixed particle size will reduce the sorting accuracy.

 

Limited processing capacity for associated minerals

The sorting effect is not good for the accompanying minerals with small density differences (e.g. sulfide, iron oxide), which need to be combined with magnetic separation or flotation. For example, magnetic pyrite needs to be removed by magnetic separation beforehand, otherwise it will be mixed in the gravity separation concentrate.

 

The gravity separation method occupies an important position in the field of tin ore beneficiation and is widely favored for its advantages of simple process, low cost, and environmental friendliness. In practical application, it is necessary to consider the nature of the ore, equipment conditions, and other factors, and carefully select the re-election process and equipment parameters, to achieve the best beneficiation indexes, to create the greatest economic benefits.