SU1079608A1 - Process for preparing wallastonite - Google Patents

Description

Q

SI

WITH

a The invention relates to the building materials industry. A known method for producing wollas tonite by synthesizing from a mixture of limestone, tripoli, and lithium carbonate fl-J The disadvantage of this method is the formation of belite contaminating the resulting product (wollastonite). Belite content, depending on the reaction conditions, reaches 15-20%. The closest to the invention in terms of technical importance and the achieved result is the production of wollastonite by roasting, at 1100–1200 ° C, a mixture of calcium carbonate and silica or natural chalk containing 30–70 silica, i.e. silica lime tz. The disadvantage of this method is the contamination of the target product, a belite, which is formed simultaneously with wollastonite during the solid-phase reaction in the CaOSiO system. The content of belit.a in the target product when roasting silica limestone reaches 20-30. The contamination of wollastonite by a belite essentially reduces its quality when used in ceramics, since it whitens, being impregnated, impairs the properties of the slip; When using contaminated wollastonite, ceramic masses based on it have a greater shrinkage than masses containing pure wollastonite. The purpose of the invention is to increase the target product by eliminating the formation of belite. The goal is achieved by those. According to the method for producing wollastonite by burning a mixture of calcium carbonate and silica at 1000–1100 in the presence of 3-5 wt. of copper sulphate, the process is carried out in the presence of copper sulphate, which is taken in an amount of 3-5 wt. .. Example 1, Sample containing 55% calcium carbonate, kQ% silica, 5% copper sulphate, calcined; no belite was found, Example 2. A sample containing 601 calcium carbonate, 35% silica, 5% copper sulphate7 is calcined at. The presence of belite was not detected .. PRI me R zo A sample containing b5% calcium carbonate, 32% silica, 3% copper sulphate is calcined at .. 3% belite is found in the sample. Synthesis of wollastonite in examples 1-3 is carried out in a laboratory furnace. Copper sulphate is introduced as a dry powder or as a solution in the form of a solution in the wet grinding of silica limestone. The samples are burned in the form of granules with a diameter of 720 mm for 0.25–0 hours. Natural limestone is obtained and the obtained products of burning are examined on a DROI-2 X-ray diffractometer with a copper cathode at a shooting rate of k degrees / min to diagnose and identify the phases formed. 20 kV, current strength 5 A. The results of X-ray diffraction studies are given in Table. 1. As follows from the table. 1, in the heat treatment products of silica limestone containing copper salt, there is a complete absence of belite and cristobalite, a sharp increase in the intensity of the main lines of wollastonite (2.97 and 3, A). This indicates 6 that with the CaO-SiO system in the presence of copper salts, the formation of wollastonite proceeds more completely. The reaction of the formation of belite, which is the usual conditions of silica-limestone with a stoichiometric ratio of SiO2 / CaO

without copper salt

1.1 0.8-1.0 As follows from the table. 2, the addition of copper salt to silica limes makes it possible to obtain wollastonite with a rather high yield from silica lime samples without maintaining stoichiometry, i.e. There is no need for preliminary batching. As a result of the use for the synthesis of wollastonite, the proposed

with salt medk

60-70

80-90 itO-SO 70-80 WIE, i.e. without copper salt, begins long before wollastonite, and then proceeds in parallel with its synthesis, in this case it does not go. Thus, it follows from the data that the copper salt performs a catalytic function, suppressing the formation of belite and promoting the formation of wollastonite. The results of quantitative phase X-ray diffraction analysis are presented in Table. 2. Table 2 Content of Colladite, May. % in the firing products of silica limestone of the method, pure wollastonite is obtained without admixture of belite, there is no need to strictly withstand the stoichiometry of the raw material and, if it is disturbed, to preliminarily do it; In addition, the use of fluids (temperature lowering agents) is not required, since copper sulfate, along with the catalyst function, also plays the role of smoothly.

Claims (2)

METHOD FOR PRODUCING WALLASTONITE by burning at 10'00-1100 ** With a mixture of calcium carbonate and silica, characterized in that in order to increase the purity of the target product by eliminating the formation of belite, the process is carried out in the presence of copper sulfate. 2. The method according to p. 1, characterized in that the copper sulfate is taken in an amount of 3 ~ 5 wt.%;