magnetic separator for sale

PTMS magnetic separation

what is magnetic separation method？

Kaolin is China's dominant non-metallic mineral resource. Kaolin is calcined with excellent light scattering ability and special ink absorption, as well as better flame retardancy and insulation. It is widely used in coatings, paper, plastics, cable insulation, construction and other industries. Calcined washed kaolin has been studied abroad. For example, the United States and the United Kingdom use soft kaolin as raw material to produce calcined ultra-fine kaolin. The industrial production technology is relatively mature. The purpose of calcination is mainly to increase the porosity of kaolinite. After removing certain dyeing impurities, the whiteness of the product can be improved.

At present, China mainly studies the calcination of coal-based kaolin, and the research on the calcination of washed kaolin is relatively rare. The commercially available washed kaolin in China generally has the defects of low whiteness, low porosity, poor ink absorption, poor surface activity and low hiding power. It can improve the above properties after calcination, so the calcined washed kaolin has good application development prospects. .

The nature of washed kaolin

The whiteness was measured, the raw material was 79.14, the pH value was 5.77, the molar ratio of SiO2 to Al2O3 was 2.03:1, which was close to the ideal value of 2:1, and the content of impurities such as Fe, Ti, K, Na was lower, and the content was less than 2 μm. It is 94.5%.

Change of whiteness after washing kaolin

Whiteness is the primary indicator of calcined kaolin. Between 450 °C and 1050 °C (constant temperature 1.5 h), the higher the calcination temperature, the higher the whiteness of the calcined product. At 1050 ° C calcination temperature, the whiteness is almost 90%. . This is because, under other conditions, the higher the calcination temperature in the same time, the thinner the solid reaction layer formed on the surface of the particles, the easier the heat conduction passes through the reaction layer, reaching the interior of the particles, and the dehydroxylation of the product. The effect is more complete and thorough, so the whiteness is higher. Therefore, increasing the calcination temperature results in a calcined product having a higher whiteness. However, when the calcination temperature is higher than 950 ° C, a new phase transformation occurs in the metakaolin to form mullite, which increases the wear value of the product. Therefore, the calcination temperature cannot be simply increased to increase the whiteness of the product.

The effect of constant temperature on the washing of high territory Baidu

When the calcination temperature is 750 °C, the constant temperature time increases, the whiteness of the product increases, especially the constant temperature increases from 10 min to 50 min, and the product whiteness increases from 74.64% to 80%, but it continues to prolong with time. The effect is gradually weakened. This is because as the time increases, the dehydroxylation of the product increases little, so the whiteness of the product increases little or even no longer, so the constant temperature of the calcined product should not exceed 1 h.

Change of oil absorption value after washing kaolin

In the range of 450 °C - 1050 °C (constant temperature 1.5h), the oil absorption of calcined washed kaolin increases first and then decreases with the increase of calcination temperature, reaching the maximum at around 750 °C, and the oil absorption at this moment is 83mL/100g. And then gradually decrease.

This is because at 450 °C-750 °C, with the increase of calcination temperature, the dehydrogenation and de-organism reaction occurs inside the kaolin, the porosity increases, and the oil absorption increases; at 750 °C, the characteristic peak of kaolinite is completely Disappeared, the internal dehydroxylation effect reached the maximum, the amount of voids was the largest, and the oil absorption was also maximized. When the calcination temperature is higher, sintering occurs, and part of the voids are closed and the particle size is increased, resulting in a decrease in oil absorption. Therefore, it is necessary to control the calcination temperature to obtain a suitable oil absorption.

Effect of constant temperature time on oil absorption value of washed kaolin

When the calcination temperature is 750 ° C, the constant temperature time increases, and the oil absorption of the product slightly increases, but the change is not obvious. Therefore, the constant temperature time has little effect on the change of the oil absorption of the calcined washed kaolin.

In summary: the calcination temperature has a great influence on the performance of the calcined washed kaolin product. The whiteness increases with the increase of calcination temperature, and the oil absorption increases first and then decreases with the increase of calcination temperature. Considering the whiteness and oil absorption, the calcination temperature should be controlled at around 750 °C.

The constant temperature time also has an effect on the performance of the calcined washed kaolin. The whiteness increased with the extension of the constant temperature time, but the high trend after 50 minutes was small, and the oil absorption did not change significantly with the extension of the constant temperature time. Therefore, the constant temperature should be controlled between 30min and 50min. Compared with coal-based kaolin, washed kaolin has the characteristics of low organic matter content, easy to achieve ultra-fine pulverization, and low wear value. Domestic washed kaolin contains more adsorbed water, structural water and some organic matter and other impurity elements, so that it has defects such as low whiteness, poor void ratio, poor ink absorption, and low hiding power. If it can be calcined to remove colored impurities and The moisture present in the structure improves the above properties, which will improve the quality of washed kaolin and increase the application field of washed kaolin, and improve the quality of domestic washed kaolin.