A method for preparing nano-calcium carbonate from limestone with high magnesium content

Abstract

The invention discloses a method for preparing nano-calcium carbonate from limestone with high magnesium content. The high-magnesium limestone is crushed, calcined, digested, sieved and aged according to a conventional method to obtain refined milk of lime; the specific gravity of the refined milk of lime is adjusted to 1.060‑ 1.080, and introduce it into the bubbling carbonation reaction kettle, control the reaction temperature of milk of lime, feed CO2 mixed gas for carbonation reaction, add sodium hydroxide and sodium polyacrylate after carbonization for 45-60min, and carbonize to pH=7.0 , which is the end point, to obtain calcium carbonate cooked pulp; add disodium EDTA to the calcium carbonate cooked pulp, keep at a constant temperature of 60-80°C for 30 minutes to obtain a calcium carbonate suspension, then add sodium stearate solution to the suspension and stir for 30 minutes to obtain Modified calcium carbonate suspension; after drying and pulverizing the modified calcium carbonate suspension, the nanometer calcium carbonate product is obtained. The nano-calcium carbonate product prepared by the invention has a regular shape, is a cube-like product, has good dispersibility, low oil absorption value, and low pH value, expands the application range of low-quality and high-magnesium-content limestone, and improves resource utilization efficiency.

Description

technical field [0001] The invention relates to the technical field of nano-calcium carbonate, in particular to a method for preparing nano-calcium carbonate from limestone with high magnesium content. Background technique [0002] Nano-calcium carbonate is a widely used inorganic non-metallic material, especially nano-calcium carbonate products because of its easy-to-obtain raw material sources, low price, high whiteness, excellent performance, less pollution in the production process, and good filling and processing performance. , are widely used in various fields such as plastics, sealants, automotive primers, paints, inks, papermaking, food, and medicine. [0003] In the industrial production of nano-calcium carbonate, high-quality limestone is usually used as raw material, and nano-calcium carbonate is prepared through steps such as calcination, digestion, aging, and carbonization, thereby avoiding the impact of metal ions such as Mg in low-quality limestone on the morp...

AI Technical Summary

Problems solved by technology

In this method, ethylene glycol and hydrogen peroxide are added in the carbonization reaction, and at the same time, the temperature and pressure in the carbonization reaction are controlled to control the crystal form and particle size of nano-calcium carbonate, and then the nano-calcium carbonate with uniform particle size is obtained through screening, which can be used in coatings. Good thixotropy and application effect; but this method requires high purity of calcium hydroxide slurry, the amount of ethylene glycol added during the reaction is large, toxic, and the product only takes nano-calcium carbonate with a particle size of ≤400nm Particles, waste, low output, high energy consumption, etc.

[0009] In summary, when preparing quasi-cubic nano-calcium carbonate, the purity requirements for the reaction raw material calcium hydroxide are relatively high, and the influence of impurities in the raw material can also be eliminated by leaching and other methods, but when using limestone with high magnesium content to prepare nano-carbonic acid In the case of calcium, magnesium ions have a great influence on the morphology of nano-calcium carbonate, but there is no effective way to remove magnesium ions from calcium hydroxide solution

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