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CN-122010151-A - Step-by-step precipitation of water magnesite and double-type compound silicon steel magnesia and preparation method thereof

CN122010151ACN 122010151 ACN122010151 ACN 122010151ACN-122010151-A

Abstract

The invention discloses a water magnesite stepwise precipitation and double-type compound silicon steel magnesia and a preparation method thereof, wherein gradient calcined light water magnesite is mixed with hydrochloric acid solution to obtain magnesium chloride solution, precipitant ammonium bicarbonate or sodium hydroxide is added into the magnesium chloride solution, A-type magnesia with CAA activity of 20-50s and B-type magnesia with CAA activity of 80-120s are prepared by stepwise precipitation, and the A-type magnesia and the B-type magnesia are regulated and controlled according to physical compound proportion to obtain the double-type compound silicon steel magnesia with average grain diameter less than or equal to 3 mu m, purity more than or equal to 99% and CAA activity of 50-80 s. The method solves the contradiction between the hydration rate and the suspension stability of the magnesium oxide of the silicon steel in a synergic way, and is suitable for preparing the high-magnetic-induction oriented silicon steel annealing isolation coating.

Inventors

  • MA JIANHUA
  • LIU MANTANG
  • YANG JIE
  • YANG DONG
  • TIAN GUANGMING
  • HE LIZHONG

Assignees

  • 西安工程大学

Dates

Publication Date
20260512
Application Date
20260130

Claims (10)

  1. 1. The preparation method of the water magnesite stepwise precipitation and double-type compound silicon steel magnesium oxide is characterized by comprising the following steps: (a) Calcining the water magnesite ore powder in a gradient way to obtain light water-boiling magnesite; (b) Mixing light-burned hydromagnesite with hydrochloric acid solution according to a solid-liquid ratio of 1 (3-5), and controlling pH and reaction temperature to obtain magnesium chloride solution; (c) Preparing A-type and B-type magnesium oxide by fractional precipitation: 1, adding a precipitator into a magnesium chloride solution according to the mol ratio of the precipitator to magnesium chloride of (1.05-1.15), controlling the pH of a reaction end point to generate basic magnesium carbonate precipitate, and washing, drying and calcining to obtain the A-type magnesium oxide with CAA activity of 20-50 s; The preparation of B-type magnesium oxide, which is to add a precipitator into a magnesium chloride solution according to the mole ratio of the precipitator to the magnesium chloride of (2.1-2.2), control the pH of a reaction end point to generate magnesium hydroxide precipitate, and obtain the B-type magnesium oxide with CAA activity of 80-120s after washing, drying and calcining; (d) Uniformly mixing the A-type magnesium oxide and the B-type magnesium oxide at a mass ratio of 1 (4-1) at a high speed to obtain the double-type compound silicon steel magnesium oxide.
  2. 2. The method for preparing the hydromagnesite fractional precipitation and dual-type compound silicon steel magnesium oxide according to claim 1, wherein in the step (a), gradient calcination is performed at three stages of temperature control, wherein the temperature is kept at 500-550 ℃ for 0.5 hours in the first stage, at 600-650 ℃ for 1 hour in the second stage, and at 680-700 ℃ for 0.5 hour in the third stage.
  3. 3. The method for preparing the hydromagnesite fractional precipitation and double-type compound silicon steel magnesium oxide according to claim 1, wherein in the step (b), the concentration of a hydrochloric acid solution is 2.0-3.0mol/L, the content of SiO 2 in a solution after acid leaching separation is less than or equal to 20mg/L, and the content of Fe 2 O 3 is less than or equal to 20mg/L.
  4. 4. The method for preparing hydromagnesite stepwise precipitation and dual-type compound silicon steel magnesium oxide according to claim 1, wherein in the step (b), the pH is controlled to be 2.5-3.5, and the reaction is carried out for 2-4 hours at 60-80 ℃.
  5. 5. The method for preparing hydromagnesite fractional precipitation and double-type compound silicon steel magnesium oxide according to claim 1, which is characterized in that in the step (c), A-type magnesium oxide is prepared, and a precipitant is added into a magnesium chloride solution to be carbon dioxide or ammonium bicarbonate solution; b, preparing magnesium oxide, and introducing ammonia water or sodium hydroxide as a precipitant into the magnesium chloride solution; The adding rate of the precipitant is 0.5-1.0% of the volume of the solution per minute.
  6. 6. The method for preparing the hydromagnesite fractional precipitation and double-type compound silicon steel magnesium oxide according to claim 1, wherein in the step (C), when the A-type magnesium oxide is prepared, ammonia water is used for adjusting the pH value of a reaction system to be 8.0-9.0, the reaction temperature is 40-60 ℃, the precipitation time is 1-2 hours, the drying temperature is 110-140 ℃ and the time is 2-4 hours, and the calcining temperature is 750-950 ℃ and the time is 1-3 hours.
  7. 7. The method for preparing the hydromagnesite stepwise precipitation and double-type compound silicon steel magnesium oxide according to claim 1, wherein in the step (C), the pH is controlled to be 9.5-11.0, the reaction temperature is controlled to be 40-60 ℃, the precipitation time is 1-2 hours, the drying temperature is 110-140 ℃ and the time is 2-4 hours, and the calcination temperature is 950-1150 ℃ and the time is 1-3 hours when the B-type magnesium oxide is prepared.
  8. 8. The method for preparing hydromagnesite stepwise precipitation and dual-type compound silicon steel magnesium oxide according to claim 1, wherein in the step (d), the mixing time is 0.5-1 hour.
  9. 9. A hydromagnesite stepwise precipitated and double composite silicon steel magnesia prepared by the method of any one of claims 1 to 8.
  10. 10. An application of hydromagnesite fractional precipitation and double-type compound silicon steel magnesium oxide in preparing a high magnetic induction oriented silicon steel annealing isolation coating according to claim 9.

Description

Step-by-step precipitation of water magnesite and double-type compound silicon steel magnesia and preparation method thereof Technical Field The invention belongs to the technical field of silicon steel annealing isolating agent materials, and particularly relates to a silicon steel magnesium oxide material based on stepwise precipitation and double-type compounding of water magnesite and a preparation method thereof. Background The silicon steel grade magnesium oxide is used as an oriented silicon steel high-temperature annealing isolating agent and an insulating film generating agent, three functions of isolation, sintering prevention, desulfurization and dephosphorization and generation of a compact magnesium silicate bottom layer are needed to be synchronously realized in the high-temperature annealing process of a silicon steel sheet, and strict requirements are put on indexes such as purity, hydration rate, suspension property and cohesiveness of the magnesium oxide. The quality of magnesium oxide directly determines the compactness, adhesion and magnetic domain thinning effect of the magnesium silicate insulating bottom layer. The preparation methods commonly used in industrialization at present comprise a brine-ammonium carbonate method, a brine-ammonia method and an ore carbonization method, but the traditional processes generally have the problems of low efficiency, high energy consumption, large environmental pollution and the like. For example, the brine-ammonium carbonate method has the defects of high difficulty in byproduct treatment, low raw material utilization rate, unstable product performance and the like. The ore carbonization method is influenced by raw material impurities, the product purity fluctuation is large, and the energy consumption is high in proportion to the production cost. In addition, the contradiction between activity and hydration rate is difficult to balance in the traditional process, hydration caking is easy to be caused by the excessive activity, and suspension property is deteriorated due to the fact that the activity can be reduced by high-temperature calcination. Disclosure of Invention In order to solve the defects in the prior art, the invention aims to provide a silicon steel magnesia material based on the stepwise precipitation and double-type compounding of water magnesite and a preparation method thereof. The preparation method comprises the steps of obtaining a high-purity magnesium source through a gradient calcination-acid leaching purification process, preparing a magnesium oxide precursor with differential activity by adopting a fractional precipitation technology, and realizing precise matching of particle morphology and reactivity through physical compounding to finally obtain the silicon steel magnesium oxide material with high purity, proper hydration rate and excellent suspension stability. The invention is realized by the following technical scheme. The invention provides a preparation method of water magnesite stepwise precipitation and double-type compound silicon steel magnesium oxide, which comprises the following steps: (a) Calcining the water magnesite ore powder in a gradient way to obtain light water-boiling magnesite; (b) Mixing light-burned hydromagnesite with hydrochloric acid solution according to a solid-liquid ratio of 1 (3-5), controlling pH value and reaction temperature, and filtering to obtain magnesium chloride solution; (c) Preparing A-type and B-type magnesium oxide by fractional precipitation: 1, adding a precipitator into a magnesium chloride solution according to the mol ratio of the precipitator to magnesium chloride of (1.05-1.15), controlling the pH of a reaction end point to generate basic magnesium carbonate precipitate, and washing, drying and calcining to obtain the A-type magnesium oxide with CAA activity of 20-50 s; The preparation of B-type magnesium oxide, which is to add a precipitator into a magnesium chloride solution according to the mole ratio of the precipitator to the magnesium chloride of (2.1-2.2), control the pH of a reaction end point to generate magnesium hydroxide precipitate, and obtain the B-type magnesium oxide with CAA activity of 80-120s after washing, drying and calcining; (d) Uniformly mixing the A-type magnesium oxide and the B-type magnesium oxide at a mass ratio of 1 (4-1) at a high speed to obtain the double-type compound silicon steel magnesium oxide. Preferably, in the step (a), the gradient calcination is performed by three-stage temperature control, wherein the first stage is kept at 500-550 ℃ for 0.5 hours, the second stage is kept at 600-650 ℃ for 1 hour, and the third stage is kept at 680-700 ℃ for 0.5 hour. Preferably, in the step (b), the concentration of the hydrochloric acid solution is 2.0-3.0mol/L, the SiO 2 content in the solution after acid leaching separation is less than or equal to 20mg/L, and the Fe 2O3 content is less than or equal to 20mg/L. Preferably, in step (b), t