Preparation method of metastable crystal phase precipitated calcium carbonate

Abstract

The invention discloses a method for preparing metastable crystal phase precipitated calcium carbonate, which comprises the following steps: (1) adding additive 1 and additive 2 into calcium hydroxide suspension and mixing, and the carbonization initial temperature is 40-60°C; 1 is more than one of group IA metal bicarbonate, group IA metal carbonate, group IA metal hydroxide, barium hydroxide or ammonia water, additive 2 is strontium hydroxide, strontium oxide, strontium chloride or strontium acetate One or more of them, feed carbon dioxide-containing gas, and when the pH of the suspension drops to 7.0 to 7.5, continue to ventilate for 10 to 30 minutes, and then collect the seed crystals from the suspension; (2) the crystal seeds of step (1) The mixture is added to the calcium hydroxide suspension and mixed with carbon dioxide-containing gas. The initial carbonization temperature is 25-50°C. When the pH of the suspension drops to 7.0-7.5, continue to ventilate for 10-30 minutes, and then remove the carbon dioxide from the suspension. The metastable crystal phase precipitated calcium carbonate is collected. The invention has low cost, obvious technological advantages and wide application prospects.

Description

technical field [0001] The invention relates to a preparation method of precipitated calcium carbonate containing metastable aragonite crystal phase. Background technique [0002] Calcium carbonate is the most widely used white filler in the world, widely used in rubber, plastics, coatings, papermaking and other fields. Calcium carbonate has three crystal phases of calcite, aragonite and vaterite, among which the calcite phase is a thermodynamically stable crystal phase, and the aragonite and vaterite crystal phases are metastable crystal phases, which are easily converted into calcite crystal phases under certain conditions. Aragonite calcium carbonate is generally needle-shaped or rod-shaped, with an average refractive index of 1.63, which is higher than the average refractive index of calcite calcium carbonate (1.58). Due to its high refractive index and special shape, aragonite phase calcium carbonate is beneficial to increase the gloss of calendered coated paper and co...

AI Technical Summary

Problems solved by technology

with MgCl 2 The main disadvantage of the preparation process for additives is that MgCl 2 The consumption is large, the cost is high, and the process requirements are complicated

[0005] There are several problems with using strontium compounds as additives: one is the high price of strontium compounds, which leads to an increase in production costs; the other is the complex mechanism of strontium, which requires a high carbonization process

As disclosed in Japanese Patent Laid-Open No. 59-223225, compounds such as strontium halogen compounds, oxides, oxy-acid salts, and organic acid salts are used as additives to prepare calcium carbonate containing aragonite crystal phases. The calcium carbonate obtained under most conditions The proportion of arsonite phase is >80%; while the content disclosed in Chinese patent application CN102834356 shows that other compounds of strontium, such as strontium chloride or strontium acetate, etc. are used as additives to prepare precipitated calcium carbonate with a relatively low arsonite phase content (<70%) , so it is not suitable as an additive for the preparation of precipitated calcium carbonate with high aragonite phase content