EXPLOITATION OF MINERALS


exploitation of minerals

In the field of extracting metallurgy, mineral processing, also known as mineral dressing or ore dressing, is the process of separating commercially valuable minerals from their ores.

Mineral processing can involve four general types of unit operation: comminution – particle size reduction; sizing – separation of particle sizes by screening or classification; concentration by taking advantage of physical and surface chemical properties; and dewatering – solid/liquid separation. In all of these processes, the most important considerations are the economics of the processes and this is dictated by the grade and recovery of the final product. To do this, the mineralogy of the ore needs to be considered as this dictates the amount of liberation required and the processes that can occur. The smaller the particles processes, the greater the theortical grade and recovery of the final product, but this however is diffucult to do with fine particles as they prevent certain concentration processes from occurring.

Comminution
Comminution is particle size reduction of materials. Comminution may be carried out on either dry materials or slurries. Crushing and grinding are the two primary comminution processes. Crushing is normally carried out on "run-of-mine" ore, while grinding (normally carried out after crushing) may be conducted on dry or slurried material.
In the comminution ,the crushing flow maybe jaw crusher,cone crusher,impact crusher,and grinding mills(roller mill,ball mill,or coarse mill).The jaw crusher and cone crusher are to crush the minerals ores into small gravel or aggregate.And the grinding mills are to grind the particle into thin powder for after sizing and concentration. The crushing may reach particle size of 10 - 100mm, and the grinding mills makes the particle into powder or ultra fine powder, such as cement, lime, etc. If you want some paint, pulverized coal or other, you need a grinding mill.

Sizing
Sizing is the general term for separation of particles according to their size.
The simplest sizing process is screening, or passing the particles to be sized through a screen or number of screens. Screening equipment can include grizzlies, bar screens,wedge wire screens,banna screens, multi deck screens, vibratory screed, fine screens, flip flop screens and wire mesh screens. Screens can be static (typically the case for very coarse material), or they can incorporate mechanisms to shake or vibrate the screen. Some considerations in this process includes the screen material, the aperature size, shape and oreintation, the amount of near sized particles, the addition of water, the amplitude and frequency of the virbations, the angle of inclination, the presence of harmful materials, like steel and wood, and the size distribtuion of the particles.
Classification refers to sizing operations that exploit the differences in settling velocities exhibited by particles of different size. Classification equipment may include ore sorters, gas cyclones, hydrocyclones, rotating trommels, rake classifiers or fluidized classifiers.
An important factor in both comminution and sizing operations is the determination of the particle size distribution of the materials being processed, commonly referred to as particle size analysis. Many techniques for analyzing particle size are used, and the techniques include both off-line analyses which require that a sample of the material be taken for analysis and on-line techniques that allow for analysis of the material as it flows through the process.

Shanghai Zenith company is found thirty years ago, and these years Zenith has been dedicated in the research of crushing and grinding technics, to reduce the cost, to improve the working efficiency, to enhance the security, to improve the operability. Since now, Zenith gets lots of archivements and the products range from crushers to grinders to screen and sand washer. Whatever you need for mining, Zenith provide. The equipments are exported to more than 100 countries now, mostly Africa, America ,Asia, and Europe. Mining machine and construction machinery are our main business.