Magnetic properties of weak magnetic minerals The magnetic properties of pure weak magnetic minerals are different from those of ferromagnetic minerals. The magnetic susceptibility of ferromagnetic minerals is variable, while the magnetic susceptibility of weak magnetic minerals is constant. It has nothing to do with external magnetic field strength, particle size and shape, but only with mineral composition. There is no remanence and hysteresis. Magnetic weakly magnetic minerals weaker, less than the susceptibility, to facilitate the study of a small number of magnetic minerals, such as hematite artifacts, titanium, iron ore is also owned by the weakly magnetic minerals, weakly magnetic minerals even at high external magnetic field, It is also not easy to achieve magnetic saturation. Weak magnetic minerals can be converted into ferromagnetic minerals by roasting, which is customarily called magnetization roasting. However, due to the different types of calcined minerals, the chemical reactions occurring during calcination are also different, so the principle of calcination is also different. According to the roasting principle, it can be divided into reduction calcination, neutral calcination and oxidative roasting. How to convert some weak magnetic iron minerals into strong magnetic minerals? (1) reduction roasting The reduction roasting is applied to hematite and limonite, and the calcination is carried out in a reducing atmosphere, and the usual reducing agents are carbon (C), carbon monoxide (CO) and hydrogen (H2). The calcination temperature of hematite is 550~600 °C, and the hematite is reduced to magnetite. The reaction is as follows: 3Fe2O3+C→2Fe3O4+CO↑ 3Fe2O3+CO→2 Fe3O4+CO2↑ 3Fe2O3+H2→2 Fe3O4+H2O↑ In the heating process, the limonite first removes the crystal water and turns into hematite which does not contain water, and then proceeds according to the above reaction. (2) Neutral roasting This kind of roasting is suitable for siderite. When roasting, when no air is introduced or a small amount of air is introduced, when it is heated to 300~400 °C, the siderite reacts as follows: No air: 3Fe2CO3 →Fe3O4+2CO2↑+CO↑ Pass a small amount of air: 2FeCO3+1/2O2 →Fe2O3+CO2↑ 3Fe2O3+CO→2Fe3O4+CO2↑ (3) Oxidation roasting Oxidation roasting is suitable for pyrite. It is calcined in a short time in an oxidizing atmosphere (or a large amount of air) and is oxidized to pyrrhotite. The reaction is as follows: 7FeS2 +6O2 →Fe7S8+6SO2↑ Further, the calcination time is extended, and the pyrrhotite is converted into magnetite by the following reaction. 3Fe7S8+38O2 →7Fe3O4+24SO2↑ This method is commonly used in the separation of the metal concentrate with pyrite roasting from rare metals.
A hydraulic manifold is a manifold that regulates fluid flow between pumps and actuators and other components in a hydraulic system. It is like a switchboard in an electrical circuit because it lets the operator control how much fluid flows between which components of a hydraulic machinery. For example, in a backhoe loader a manifold turns on or shuts off or diverts flow to the telescopic arms of the front bucket and the back bucket. The manifold is connected to the levers in the operator's cabin which the operator uses to achieve the desired manifold behaviour.
A manifold is composed of assorted hydraulic valves connected to each other. It is the various combinations of states of these valves that allow complex control behaviour using a manifold.
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