Introduction to the new method of broken ore

If we study the crushing process from the point of view of energy balance, we can see that the input energy is consuming sound, heat, chemical changes, wear parts of the crusher , friction loss of the machine transmission system, and micro cracks and formation of the object. New surface and other items. As far as the purpose of the broken ore is concerned, only the last two items are useful, and others are losses. Previous researchers have calculated the theoretical efficiency of ball mill milled quartz . If only the surface energy on the new surface area is considered, then only 0.06% of the input energy is useful. Those losses although it is difficult itemized determination, but only in respect of a large steel mill consumption of view, can be realized wear steel energy consumption is very alarming. In order to improve the crushing efficiency, while improving the existing equipment, the new methods of crushing ore "stones, such as electrothermal irradiation, liquid electricity effect, thermal crushing, decomposing crushing and crushing methods using other energy sources, etc. are also studied. However, In addition to the semi-industrial comparative test of the Snyder decompression method, it may be quickly applied in industry, and the others are only initial studies.
The principle of electrothermal irradiation is that under the action of high frequency and ultra-high frequency electromagnetic fields, minerals that are easy to absorb electromagnetic energy are heated abruptly, and other minerals only rely on heat conduction to obtain heat. The different heating rates cause temperature stress between the minerals, and the original strength is reduced by about 1/2~3/4. In the United States, the fractured iron shale was tested under a coil magnetic field of 4 to 7 megacycles and 25 kilowatts. The Soviet Union studied granite under 0.5 to 50 megacycles and 6 to 14 kilovolts of capacitors.
High-pressure and instantaneous pulse discharges are carried out inside the liquid, and extremely high pressure is generated in the discharge region, which can break the object. This effect is called a liquid-electric effect. This method has been used as a crushing test for large ore. In the discharge circuit of 65 kV, 45 microfarad and 25 microhenry , the unqualified large blocks such as granite and quartzite are broken, and the energy consumption per cubic meter is about 0.05~ 0.15 kW • hour. This method has also been used to test 100 × 70 × 50 mm shale , jasper iron and horn rock to below 5 mm.
The thermal fracture studied in mineral processing is actually the combination of heat and mechanical force. The ore is weakened by heat treatment, and then it is broken by machinery to improve the crushing effect. A few years ago, the US Bureau of Mines discovered that a - spodumene senescence at 1000-1100 °C and turned into a soft and easy-to-wear beta-spodumene. In mineralogy, it is pointed out that β-quartz becomes a quartz at 573 °C and the volume increases by 2.4%; a-quartz becomes a-scaly quartz at 870 °C, and the volume increases by 12.7%; a-scale quartz becomes a- at 1470 °C. Fang Yingshi, volume increased by 4.7%, volume expansion will bring tensile or shear stress damage, so quartz-bearing rock is more conducive to thermal fracture test. Tests using quartzite indicate that the sample is heated to 600 ° C, then quenched or slowly cooled by water, the sample expands significantly, the tensile strength is reduced by about half, and the fine grade yield in the ball milled product is thus greatly increased. K. Hatton Harlan and others heated the quartz to 400, 500, 600, and 700 ° C, and then cooled in water, the quartz became easy to grind, and the Bundesligibility index decreased. Heat treatment is used to improve the grindability, and other researchers have tested quartz-containing or quartz-free minerals. The results confirmed that thermal stress due to heat treatment can improve the grindability and have a positive view of economic rationality.
H. Snyder's schematic diagram of the equipment used in the decompression method.
The crushed material is placed in the pressure chamber 2, and steam or other compressible fluid is introduced from the load valve 1 at 5.6 to 52.5 atmospheres, and then the conduits are opened by the quick valve operating device 3 in 15 microseconds. The fluid under high pressure suddenly decompresses and expands, that is, carries the ore to flow along the conduit at near-sonic or supersonic speed. The conduit in the figure is a "double-gun system" that collides with the high-speed material flowing along the two conduits and then enters the circular shape in the middle. A collection chamber where the broken product is collected. It is shown that several pairs of dual lance devices can be coupled to a common collection chamber. Some devices use a single gun device. A cycle is completed in 15 to 30 seconds from the addition of the mineral material and the introduction of the high pressure fluid to the reduced pressure ore. At present, the capacity of such equipment has reached 6.5 ft 3 (184 liters), processing capacity of 57 tons / hr, can handle 2 inches (5.1 cm) of materials, and will soon test 90 tons / hr of equipment. It is preparing to design 800 tons / hour equipment, can handle 6 inches (15.2 cm) of materials.

Figure k Schematic diagram of the equipment used in the Snyder decompression method 1. Load valve; 2. Pressure chamber; 3. Rapid valve operating device; 4. Spray conduit

When the high-pressure gas suddenly releases, the volume immediately expands and moves at the speed of sound or supersonic speed, causing a strong shock wave and acting on the mineral material. The shock wave is reflected at the grain boundary inside the ore, and the grain boundary is subjected to tensile stress. The kinetic energy of the high-speed moving fluid is more effectively transmitted to the ore particles, and the high-frequency collision between the ore particles is beneficial to the fracture. Therefore, it is physically different from the method created by the US Mining Bureau RS Dean in 1930, which uses pressure to compress and coagulate vapors in the micro-cracks of the ore, which expands under sudden decompression, thereby breaking the ore. The characteristics of the Snyder decompression method are since the tensile stress caused by the shock wave at the grain boundary breaks the ore, so the crushing is easier, and a higher degree of dissociation can be obtained in the coarser crushed product.
Comparative test semi-industrial magnetite, porphyry copper ore, copper-nickel ore, bauxite and asbestos mineral aggregate is made that since Snyder reduced pressure crushing method has a tensile stress along the grain boundary broken ore The characteristics of the product are higher than that of the ball mill or the rod mill, but the crushing is lighter, and the recovery rate and concentrate grade are higher. Snyder equipment is light in weight, easy to repair, does not require a heavy foundation, has a small plant area, few moving parts, less wear and less loss in energy conversion, these advantages make its investment costs and The operating fee is relatively low. According to the economic estimates made by the company, it can outweigh the ball and rod grinding, and it is better than self-grinding. All new equipment and new processes must pass a long time and a wide range of production inspections in order to clarify its advantages and disadvantages. Although the Snyder decompression method has shown many of the above benefits, its development And the application of industry, there is still to be further research in the future.

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Box anchor construction can be used for following purposes:
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The box anchor consists of:

- a box anchor

- three anchoring pins with local reinforcement plates

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- one hosting eye of 200T

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