Method for preparing chromium-containing magnesia from magnesite light burning powder
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A light-burning powder and magnesite technology, applied in the field of magnesia preparation, can solve the problem of uneven particle size distribution, achieve the effects of good uniformity, avoid falling off and separation, and reduce the calcium content of the product
Inactive Publication Date: 2018-05-18
CENT SOUTH UNIV
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Due to the coarse particles of lightly burned powder, the distribution of particle size is uneven, and the control conditions make the particle size of chromium hydroxide increase so that it is difficult to achieve uniform particle size of lightly burned powder.
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Embodiment 1
[0065] A method for preparing chromium-containing magnesia from lightly burned magnesite powder, comprising the following steps:
[0066] Step (1): Pretreatment: first, lightly calcined powder is calcined at 900°C for 1 hour;
[0067] Step (2): Hydration and decalcification: hydration treatment of lightly burned powder, hydration temperature 30°C, stirring hydration time 0.5h at 200r / min, to obtain a solid content of 40wt% pulp (Ca 2+ Concentration 1.37×10 -4 mol / g), add 10ml1mol / L Mg to the pulp 2+ Salt solution, carry out decalcification, 200r / min carry out stirring and stirring 0.5h to obtain decalcification ore slurry (Ca 2+ Concentration 3.97×10 -5 mol / g);
[0068] Step (3): Precipitation of chromium: Add 5ml of 0.3mol / LCr to the decalcified ore slurry 3+ Salt solution, then stirred at 30°C and 400r / min for 0.5h to carry out chromium precipitation reaction, solid-liquid separation, to obtain the precursor filter cake:
[0069] After cooling to the same temperature, ...
Embodiment 2
[0075] Use more sufficient hydration process to carry out the following experiments:
[0076] Step (1): Pretreatment: first, lightly calcined powder is calcined at 900°C for 1 hour;
[0077] Step (2): Hydration and decalcification: Hydrate the lightly burned powder at a hydration temperature of 70°C and stir at 200r / min for 0.5h to obtain a pulp with a solid content of 40wt%, and add 10ml to the pulp 1mol / L Mg2+ salt solution for decalcification, stirring at 200r / min for 0.5h to obtain decalcified ore slurry;
[0078] Step (3): Chromium precipitation: Add 5ml of 0.3mol / LCr3+ salt solution to the decalcified ore slurry, then stir at 70°C and 400r / min for 0.5h to carry out the chromium precipitation reaction, and separate the solid and liquid to obtain the precursor filter cake:
[0079] After cooling to the same temperature, chromium salt was added for chromium precipitation. The composition analysis of the precursor filter cake is shown in Table 2.
[0080]
[0081] Step ...
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Abstract
The invention discloses a method for preparing chromium-containing magnesia from magnesite light burning powder. The method is characterized by comprising the following steps: pretreating light burning powder at the temperature of 850 DEG C or higher to obtain pretreated light burning powder; hydrating the pretreated light burning powder with water to obtain ore pulp, adding a magnesium source tothe ore pulp, and removing calcium to obtain calcium-free ore pulp; adding a Cr source to the calcium-free ore pulp; performing chromium precipitation reaction, and performing solid-liquid separationto obtain a precursor; and sintering the precursor to obtain the chromium-containing magnesia. Through a lot of researches, inventors find that the light burning powder is preheated to the set temperature so as to be pretreated, then hydration is preformed, the magnesium source (providing Mg<2+>) is added to the ore pulp obtained by hydration, calcium hydroxide impurities are converted through theprecipitation conversion mechanism, and then, the Cr source (providing Cr<3+>) is added; and through the precipitation conversion mechanism, formed chromium hydroxide is avoided from falling and separating from the surface of a magnesium oxide source, and the uniform dispersity of the chromium hydroxide in the precursor is greatly improved, thereby obtaining the chromium-containing magnesia withexcellent performance.
Description
technical field [0001] The invention belongs to the field of magnesia preparation, and in particular relates to a preparation method of chromium-containing magnesia. Background technique [0002] Lightly burned powder is lightly burned from magnesite at 750°C to 1100°C. The main component is magnesium oxide. Depending on the place where the magnesite is produced, it often contains a small amount of impurities such as iron, silicon, and calcium. Lightly burnt powder is mostly produced in Liaoning and other places. It is cheap and has a wide range of sources. The market price is about 500 yuan per ton. The method of directly depositing chromium compounds with lightly burned powder as the base material has the advantages of simple process and low cost. [0003] Magnesia refers to the material with MgO as the main phase. It is commonly known as magnesium oxide. It is a white or light yellow blocky solid. It has the characteristics of high refractoriness and strong resistance to...
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