Properties chemical physical changes of raw materials

The related properties of raw materials will affect the design of electric melting furnace, the choice of control strategy the formulation of energy saving scheme. Therefore, it is necessary to introduce analyze the raw materials. At present, most of the raw materials used in electric melting furnace are siderite powder slag

Light burned iron powder is the main case.

(1) Before siderite

Density of concentrate powder

For siderite powder, generally, the siderite ore on the mine is crushed by the grinding truck then directly used as raw material without any other process. Such raw material is called siderite powder. It is a natural siderite a carbonate mineral of the triangular system. The common magnesite powder is grayish white gray, its particle size range is generally 0-15mm. The density is between 2.x1i0'kg / M " 3.1xi" kgym ", the Mohs hardness is between 3.5 45. Its mineral composition is relatively simple, belonging to calcite. The main minerals are rhomboclase dolomite, the secondary minerals are talc. Clinopyroxene, as well as relatively abundant minerals such as quartz amphibole. The results show that the content of beryl, limonite, pyrite, etc. The chemical composition of magnesite is almost entirely composed of MgCO, which is 47.82% MgO 52.18% CO in theory. The main chemical components of impurities are Cao, 810, Ra0 410. The impurities contained in the new hematite can promote its burning, but when the content of Qinshi is high, its fire resistance will be greatly reduced. Therefore, the content of impurities should be limited. Since siderite is carbonate, its calcination reacts with decomposition. In fact, at the beginning of the reaction, there is a large amount of carbon dioxide decomposition mass loss in the oxidation zone. The reaction equation of this process is: at this time, the MgO formed is loose, without a real lattice, with high chemical activity easy to be solved. When the temperature is kept away heating, the size of the body the chemical activity decrease. At the same time, the impurities CSO, 8i0, PE. O, 4l0 Ugo form compounds with lower melting point. When the temperature is above 1910k, the lattice trapping of MgO is restored corrected, the crystal correction develops gradually with the increase of temperature. The organizational structure is fine. When the temperature reaches 9200k of the lattice point, the raw materials will be separated step by step, their chemical physical properties will reach the standard. After natural cooling, large-size high-purity crystals will be obtained. Above: the process is also the main stage the original into the furnace to the finished product output. the point of view of temperature change, it can be divided into ygco, opening process, MgCO, decomposition process, MgO opening process, Mg0 melting process Mg0 solidification crystallization process.

(2) Light burned magnesium powder

At the moment of sale, light burning magnesium will be the key to lock up the mine. The product of light sintering. Light burned magnesia powder is equivalent to siderite: the process of adding i t for primary top treatment. It can be divided into heavy burned iron powder light burned iron powder according to the strength of sliding sintering of siderite. The scientific name of light burned magnesia powder is magnesia, its chemical formula is Ugo. It is commonly known as siderite light burned magnesia powder, which is a kind of nz0. It can be seen the previous discussion that the light burning of mirror powder is one of the many changes of MgO. At room temperature, the density is 19x18'zg / M 'to yellowish powder. Under the action of heat energy, with the change of temperature. Cooling crystal is the product of electric melting sand locking. It should be noted that as a result of high-temperature calcination, there will be mass loss in the most burning process. In fact, when the furnace mouth is open, a certain amount of raw materials will be released with hot gas, the loss is about 5% to 10%. In order to judge the sintering degree of magnesite, the true density, re sintering shrinkage hydration properties are often used to measure the roundness. The appearance color of magnesite can also be used to judge grade the roundness. The calcined pure siderite is white. Under the influence of impurities, such as iron oxide, its color will be brown tan. When the calcium content is high, its color is close to white yellow, dark brown when the calcium content is high, black when the calcium content is high