Basic knowledge of mineral processing

Company expert group Zheng Guangwei

First, the basic concept of mineral processing

    (1) crushing and screening

    (2) Grinding classification

    (3) Sorting (flotation)

    1. Flotation agent

    2, flotation machinery

    3. Flotation process

    4. Calculation and evaluation of efficiency indicators and production processes in the flotation process

    (4) Concentrate dehydration

    (5) Tailings Dam

    (6) tailings transportation

    (7) Inspection and control of the production process

Second, the purpose, tasks and processes of mineral processing

    (1) Purpose, task

     Mined from the mine ore grade is generally relatively low, such as copper ore is only about 0.5-1.5%; such a direct smelting ore is not only technically difficult, but economically uneconomical. In order to meet the requirements of smelting, the need for low-grade ore beneficiation processing the separated useful minerals and gangue, is useful to improve the metal content of the ore, and smelting to obtain raw material suitable for the requirements of other sectors.

    The ore often contains a variety of useful ingredients. In order to fully utilize the national mineral resources, they must be recycled as much as possible to select individual concentrates that meet the requirements for further processing and utilization.

    In addition, the ore often contains impurities harmful to the treatment of the component. In the smelting, harmful impurities entering the metal will affect the quality of the metal, which sometimes complicates the smelting process and is even difficult to carry out. For example, the harmful impurities in copper concentrate are zinc , and the harmful impurities in zinc concentrate are iron . Therefore, it is necessary to try to remove or reduce the content of harmful impurities during the beneficiation process.

    The basic purpose and task of mineral processing is to separate useful minerals from gangue, separate symbiotic useful minerals into separate concentrates as much as possible, remove harmful impurities, and fully and economically and comprehensively utilize national mineral resources. Mineral processing cannot directly extract a certain metal from the ore, but only a useful mineral can be separated from the ore.

    (2) Beneficiation process

    In order to separate the useful minerals and gangues from the ore, the ore must first be broken down to the extent that the useful mineral monomers are separated. This degree is called monomer separation or dissociation. Only when the useful minerals are dissociated from the ore in the ore can different mineral processing methods be applied and selected. To this end, the ore that enters the concentrator (usually called ore) usually undergoes preparatory operations such as crushing, sieving, grinding, and grading.

    After the raw ore is selected, the final product suitable for smelting processing with high useful mineral content is called concentrate. The product left after the concentrate is separated, the product with very low useful mineral content, no further treatment or technically and economically unsuitable for further processing is called tailings.

    During the beneficiation process, some semi-finished products are sometimes separated, and the products that need further processing are called mines.

    The concentrate obtained from the selected results needs to enter the dewatering operation (concentration, filtration, drying, etc.), so the entire beneficiation process is a continuous continuous production process, usually consisting of the following basic operations: crushing, grinding , select points, transfer dehydration, etc.

    The abandoned tailings are stored by hydraulic transfer to the tailings dam.

Third, the beneficiation process overview

    (a) broken

    Ore is a natural heterogeneous body composed of various minerals of different shapes, different particle sizes and different physical properties. The process of changing the ore particle size from large to small is called breaking. According to the crushed raw materials and the required product particle size, the crushing operations can be roughly classified into coarse crushing, medium crushing, and fine crushing. Generally, the final crushed product has a particle size of less than 20 mm.

    (2) Screening

    A job in which a particle size range having a wide particle size range is classified into a level by a sieve is referred to as screening. Screening operations are often associated with crushing operations. To improve crushing efficiency, the ore of acceptable size is separated prior to crushing. The sieving is divided into independent sieving, preparation for sieving, auxiliary sieving, and selection of sieving.

    (3) Grinding

    Grinding operations are one of the prerequisites for achieving separation of various mineral particles in ore and for smooth sorting. Under current conditions, mechanical grinding is the main method to achieve monomer separation of mineral particles.

    The merits of the selection index (concentrate quality, recovery rate) depend to a large extent on the degree of separation between mineral particles. If the grinding fineness is not enough, or the overgrinding will deteriorate the beneficiation index. Insufficient control of the fineness of the former often results in the loss of the continuous body in the tailings. The over-grinding will cause the ore to be muddy, and the fine-level particles are difficult to recover, reducing the recovery rate and affecting the quality of the concentrate.

    (4) Grading and grading efficiency

The grading operation is of great significance in the grinding cycle. Because the useful minerals of the fine particle embedded portion are dissociated and sorted, the ore must be ground to the appropriate fineness, but at the same time, the effects of over-grinding and muddy must be avoided. Therefore, the grinding products are classified in time, and the qualified products are separated into the sorting operation, and the unqualified coarse grades are returned to the grinding and regrind. In the configuration, the classifier often forms a closed circuit with the ball mill .

(5) Flotation

Flotation is a wet sorting process in which the mined ore emerges from the suspension of water (pulp) according to the physicochemical properties of the mineral surface. At present, the foam flotation method is generally applied. The essence of the method is to grind the ore with water to form a slurry, add it to a flotation agent, then stir it in a flotation machine, and introduce air to form a bubble, so that a part of the floatable mineral adheres to the bubble, and The foam floats to the surface of the slurry to form a foam, which is a foam product, called a concentrate. Another part of the non-floating gangue, which cannot adhere to the bubbles and remains in the slurry, is often referred to as tailings. In this way, the purpose of separation is achieved. In short, the flotation process is the separation of useful minerals from the gangue in the ore.