Talk about the experience of the mill miner skill training course

　　The skills training course for miners should highlight the practicality, pertinence, scientificity and popularity of the training.

　　In the process of grinding skills appraisal training, students often mention the question is: can't remember, how to do?

　　In the training, problems like this will be encountered: what is the influence of grinding particle size on the selection index? The textbook is described as follows: "all kinds of different beneficiation methods are limited by the particle size of materials, and the grinding products are too coarse and too fine, which is unfavorable to the selection process. When the ore is too coarse, the dissociation degree of useful minerals and gangue mineral monomers is poor, and it is difficult to separate the useful minerals in the process of separation. The grade of the selected concentrate will not be high, but the grade of tailings will increase, which reduces the recovery rate of useful minerals. It is difficult to recover the grinding products through detailed rules, because the particles close to colloidal fineness are difficult to control with the current sorting method. The sorting operation selects qualified product concentrate, which generally has high water content and cannot be stored and transported without dehydration. The influence of mineral particle size on dehydration is not small. The mineral particles that are too fine are not easy to settle and send to the bottom filter of the thickener during concentration, often by the thickener overflow loss to the tailings, resulting in metal loss. In order to reduce the difficulty of concentrate dewatering, improve the grinding efficiency, and ensure the best grinding particle size is the key to obtain the best concentrate quality."

　　This paragraph can be understood by the participants. But can't remember.

　　Analyze together with the trainees: the fundamental purpose of grinding ore is to ensure the granularity of the selection operation and finally the selection index. The selection indexes to be ensured are: while ensuring the concentrate grade, try to improve the recovery rate and reduce the tailings grade. At the same time, the concentrate moisture should meet the requirements, that is, to ensure four selection indexes: high quality, high yield, low tail and low moisture.

　　What is the state of granularity? Either too coarse or too fine. What are the adverse effects of too coarse and too fine on the above four indicators?

　　Too coarse, monomer dissociation degree is poor, even more. The continuous growth into concentrate, the fine quality is low, the continuous growth into tailings grade, the tail product is high, the yield is low at this time; (Students are required to draw a double line under the "keyword")

　　Too fine, fine mineral processing is the world problem, easy to cause metal loss, dehydration difficult. (Ask participants to double-line under "Keyword")

　　Therefore, when answering the question of "What is the impact of grinding granularity on the selection index?", it is suggested that students should grasp the key words: "Too coarse and too fine granularity is unfavorable:

　　Too coarse, poor monomer dissociation, low quality, high tail, low yield;

　　Too fine, fine particles are difficult to choose, metal is easy to lose, dehydration is difficult."

　　The understanding of anything has to go through the process from simple to complex, and then from complex to simple. In this process, people constantly improve their cognitive ability. This may be called progress.

　　Not all problems can be solved so easily.

　　Senior miners are mostly team leaders at the scene, so in the process of communicating with these students, there is a problem that cannot be avoided: what is the problem with the low qualified rate of grinding particle size? The answer to the textbook is this: "The particle size qualification rate is used to measure the quality of grinding products. The high qualified rate of particle size indicates that the grinding machine has a high level of operation technology under the same operating conditions (referring to the particle size, hardness and amount of raw ore), which makes the grinding equipment play a full role. Due to the high qualified rate of particle size of grinding products, good conditions are created for mineral processing. The low qualified rate of particle size indicates that under the same operating conditions, the technical level or sense of responsibility of the operator does not meet the requirements, which brings adverse effects to the beneficiation operation and causes the consequences of low concentrate quality. Even if a skilled miner operates carefully and adjusts carefully according to the operating procedures under unfavorable operating conditions, he will obtain a higher particle size qualification rate."

　　The participants generally agreed with this answer. But feel the train of thought is not clear. Perhaps the task of training teachers in this problem is to help students clarify their ideas: why should they examine the qualified rate of particle size, which is used to measure the quality of grinding products. What does the low pass rate mean? We know that grinding is a process in the whole ore processing process. From the perspective of management, the 5 factors that affect the quality of a 1 process are: people, machines, materials, methods and rings. We are required to use the 5 elements of quality management to analyze the reasons that affect the quality of the grinding process, that is, the low pass rate of grinding particle size.

　　Ignoring the influence of "environmental" factors on the grinding operation, students are required to find the four elements of "man, machine, material and method" that affect the qualified rate of particle size. That is, "grinding miners, grinding equipment, raw ore, operating procedures". Draw "Fishbone Figure 1"

　　Brainstorming: Let the students write down the possible reasons for the low granularity pass rate of each element, and then summarize and draw fishbone diagram 2.

　　So there is the following resonance: grinding particle size qualified rate of low description:

　　The qualified rate of particle size is used to measure the quality of grinding products.

　　1. Under the condition that the raw ore remains unchanged: the low qualified rate of particle size indicates that the technical level or sense of responsibility of the grinding miners have not met the requirements, or they have not been able to operate according to the operating procedures, and they have not been able to make the grinding equipment play a full role, which will bring adverse effects to the beneficiation operation and cause the consequences of low concentrate quality.

　　2. A skilled and high-level mill miner, even under the unfavorable conditions of changes in the original ore, careful operation and careful adjustment, will obtain a higher particle size qualification rate. (The human factor is important.)

　　If the first and intermediate miners can draw "fishbone diagram" 1, it is already very valuable. Senior miners and grinding technicians have a good interpretation of "fishbone diagram" 2.