The reason why kyanite can be widely used in all aspects of national production is mainly due to the following excellent process characteristics:
(1) Refractoriness. The refractory material using kyanite as raw material has a refractoriness of more than 1790 ° C and a maximum of more than 1850 ° C. For general clay refractories, the refractoriness is 1670 ~ 1770 ° C.
(2) Thermal expansion. Kyanite is gradually converted into a mixture of mullite and white silica when heated, and is accompanied by volume expansion during this conversion, and the general volume expansion ratio is 16% to 18%. There is no change in kyanite crystal below 1000 °C. When the temperature reaches above 1300 °C, it gradually begins to change into mullite and white silica. The volume expansion of kyanite is mainly divided into three stages, namely, the gradual period, the dramatic period, and the falling period.
(3) Stability. Compared to the use of clay as a refractory, refractories made with kyanite minerals are 1.5 times more stable and have a loss of 43% lower. At the same time, kyanite has good chemical inertness due to its strong acid and alkali resistance and even hydrofluoric acid, and it also has good volume stability.
(4) Irreversibility. Below 1810 ° C, the conversion of kyanite minerals into mullite is a stable and irreversible process. Therefore, the refractory material made of mullite after blue crystal petrochemical has the characteristics of stable volume at high temperature, low expansion ratio, strong chemical corrosion resistance, high mechanical strength and strong thermal shock resistance.
China's kyanite resources are mainly distributed in Henan, Jiangsu, Shanxi, Liaoning, Hebei, Xinjiang, Anhui and other places. The kyanite deposit is dominated by regional metamorphism and is mainly produced in schist, gneiss and quartzite . Among them, Henan Nanyang Hidden Mountain, Nanyang Tongbai and Jiangsu Muyang Kyanite Mine have good quality and large reserves, and have completed the ore dressing test. At present, most of the domestic kyanite concentrate products are from the Nanyang kyanite mining area, which has the largest market share and good grade.
The kyanite extracted from the mine has only a small number of rich ore-rich minerals, and most of them are composed of useful minerals and gangue minerals, and contain iron minerals, minerals containing minerals, graphite , carbonaceous materials, etc. Its material composition is relatively complicated, the ore grade is generally low, can not be used directly, must be subjected to beneficiation and purification treatment, increase the content of useful ingredients, exclude most of the gangue and other harmful components, so that useful minerals can be integrated into concentrates before use. .
Flotation can adapt to the beneficiation of various complex mineral inlay types of kyanite ore, so it becomes the main sorting process of kyanite minerals, and has been widely used in the beneficiation of kyanite minerals at home and abroad. Depending on the type of ore and the type of collector , kyanite flotation can be carried out in acidic, neutral or alkaline media. At present, kyanite flotation process at home and abroad focused on the main factors affecting the flotation operations, including grinding fineness, aspects desliming effect, pulp pH, inhibitors and metal cation. The optimal particle size of flotation is related to particle shape, specific gravity and degree of hydrophobicity. One of the reasons why the recovery rate of kyanite flotation is difficult to increase is that the loss of recovery rate is often caused by the falling off of coarse particles during the floating process of kyanite. According to the flotation theory, the contact area between the unit weight of the mineral particles and the flotation bubble has an important influence on the adhesion strength of the particles and the bubbles. The kyanite crystals generally have a long column shape and a needle column shape. Even after the kyanite is ground, the crystals are still needle-like and elongated, and the bubbles are mostly in contact with the crystal end faces having a small area, and at the same time, the blue crystals The specific gravity of the stone is larger than most of the associated gangue minerals such as quartz , feldspar and mica , so that the coarse-grained kyanite ore is easy to "fall off" from the bubble, thus affecting the recovery of flotation.
At present, the processing technology of domestic kyanite concentrator is relatively backward and the production cost is high. Most of them are only processed through simple processing, resulting in low product quality, high impurity content and unstable quality, and lack of competitiveness in domestic and international markets. In order to give full play to the resource advantages of China's kyanite mine, the primary problem to be solved is to study economically rational beneficiation technology for application in production practice. In order to solve many problems in the processing of kyanite ore, the development direction of kyanite beneficiation processing in China is mainly as follows:
(l) According to the characteristics of China's kyanite mine, carry out in-depth and systematic research on the fundamentals of process mineralogy and mineral processing, and provide theoretical guidance for the formulation of a reasonable beneficiation process. The main factors affecting the flotation of kyanite should be studied in detail, including the study of the mechanism of action of the agent and kyanite, the inevitable study on the influence of metal ions on the flotation of kyanite, and the experimental research on the process of mineral processing.
(2) Improve resource utilization. According to the characteristics of the associated minerals of each ore, a reasonable mineral processing process is formulated to comprehensively recycle and use associated minerals such as Qin, iron and mica to improve economic benefits.
(3) Promote the use of high-grade refractory materials such as kyanite. The consumption of high-grade refractories of kyanite in foreign countries has increased year by year, while the consumption of low-grade refractories of clays has shown a downward trend. The huge demand for kyanite minerals in the market will inevitably lead to a rapid increase in the production scale and mineral processing technology of kyanite minerals in China.
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