The process of the formation of residual placer tin ore is gradually accumulated and accumulated, and it is mainly due to the long-term weathering and wear of primary tin ore to the gradual reduction of particle size. Most of the tiny particles involved in this may have taken thousands of years of natural action to form. Here's a detailed explanation of why the grain size of residual placer tin ore becomes very small.
1. Weathering.
Surface weathering is an important reason for the finening of ore particles. Weathering usually includes physical weathering and chemical weathering. Physical weathering is mainly caused by cracking and fragmentation caused by natural forces, such as wind, water, ice, etc., acting on ores. Chemical weathering is mainly through the contact between the ore and the atmosphere, water, etc., and chemical reactions such as oxidation, hydration, and carbonate occur, thereby changing the properties of the ore, making it more fragile and the particles finer. Weathering is one of the main processes for the formation of residual tin ore.
2. Sedimentation.
With the action of natural forces (such as wind, spring water and rainwater flow, etc.), the sand-like tin ore particles that have undergone weathering will move and migrate, and eventually form deposits in the riverbed, riverbank beach, leaching slope surface, foothill fields and other places. In this process, coarse-grained and fine-grained minerals will be classified and deposited due to their differences in physical properties such as specific gravity, shape, hardness, etc., and the fine particles that cannot be deposited in this process will be moved away from the original ore deposit and migrated to other places with the action of feng shui, making the raw ore particles smaller in size.
3. Denudation.
After the ore is weathered, the long-term erosion of wind and water will also reduce the particle size. Denudation mainly includes two processes: mechanical abrasion and dissolution. Under natural conditions, the surface of the ore will be continuously eroded and dissolved by natural forces such as wind, rain, ice and snow, etc., so that the particle size will gradually decrease.
Fourth, the role of artificial excavation.
Anthropogenic mining and processing activities may also result in smaller ore particles. Blasting and striking during the excavation process, as well as beneficiation processes such as washing and grinding, will further break the raw ore and make the particles smaller.
5. Biological effects.
Biological influences are another important factor. Biological processes, including microbial corrosion and plant physiology, can change the material composition and structure of mineral deposits, which in turn affect the size of mineral particles.
6. Microscopic factors.
Microscopic factors, including the crystal structure and composition of the mineral, can also affect the particle size of the mineral. Physical properties such as hardness, toughness, and brittleness of the ore affect its ability to resist weathering, which in turn affects its final particle size.
Therefore, the reason why the ore particles in the residual placer tin ore become very fine is the result of a combination of long-term weathering, sedimentation, denudation, excavation, biological action and microscopic factors. These natural forces and human activities have resulted in the formation of a fine-grained, widely distributed residual placer tin ore.