The first grinding stage of the mining process
The main advantage of a period of grinding process is: a small number of the grading machine, lower investment; easy adjustment is simple; transport of intermediates between the segments, and series of grinding machine can be placed at the same level , thus the configuration of the device is relatively simple; stage grinding machine or grading machine downtime will not affect the work of another grinding section, and thus to lay-off loss; each series can be installed on larger equipment. By stage grinding process, the mill open easily crush phenomenon. Typically, mill and grading agencies into a closed loop. Commonly used process has the following three types: Figure 3-16.
Check the grading period of the grinding process is the most widely used section of the grinding process. Ore directly gives the mill, to mine the most suitable particle size is 6-20 mm. Grinding the product to enter the check sorting machine to separate the grain size of the most qualified, unqualified grain size returns grinding bodies to cyclic loading. Check the grading machine and mill closed, on the one hand can control the maximum particle size of the qualified product; the other hand, due to the presence of cyclic loading, increase per unit time by the number of mill ore, shorten the time of the ore through the mill, which can reduce the crush phenomenon, and can improve the grinding efficiency.
When the soluble salts contained in the handle contains a large number of fine ore (15%) qualified products, or necessary to the original ore mud and ore pre-separation of the separate treatment, can be used with the pre-grading and inspection of grading period of The grinding process. The purpose of pre-graded to remove the product qualified by the mill to the mine size, thereby increasing the production capacity of the mill; or separation of the slime in order to be dealt with separately. Pre-classification is generally a mechanical grader, in order to prevent mechanical wear too much, to the upper limit of the ore particle size should not exceed 6 ~~ 7mm. In order to pre-grading, not less than 140 / o 15% of qualified grain quality score to mine. Pre-grading points out native slime and soluble salts, and the nature of the ground product, separate treatment can improve the sorting indicators. If there is no separate treatment is necessary, the process in the pre-grading operations and inspection of grading operations can be combined into a single job.
When the smaller the product, or in a period of grinding conditions must make use of a grinding process stage of sorting can be used with the control of the grading period of the grinding process. During mechanical grading, there is always some failed in the granularity of particles inevitably mixed with the overflow control, grading can get a smaller size. However, this process, check the classification of the overflow of mine is greater than the original ore weight of the larger classification of surface; cause the mill feed size non-uniform, rational ball difficult to make grinding efficiency; and because of the changes was the separation of the overflow traffic, the resulting classifier is not stable. These reasons limit the application of control grading.