What are the classification and main characteristics of silica raw materials for silica bricks?

In industry, siliceous rocks are usually called silica, and can be classified into vein quartz, quartzite, quartz sandstone and chert according to the type of rock or cause of formation. The main component of silica is SiO2, and the others are impurity components. Silicas can be classified by their degree of crystallinity, density, and rate of transformation. The chemical composition and physical properties of silica have a significant impact on brick making. The production of silica bricks must formulate reasonable process regulations and systems according to the characteristics of raw materials. Silica is divided into two categories according to its crystallinity: crystalline silica and cemented silica.


Cemented silica is a sedimentary rock composed of quartz particles bound by siliceous cements. The cemented silica is mainly quartz, with a small amount of feldspar and mica. The cement is siliceous, such as chalcedony, opal, etc. The quartz particles are small (0.01mm), and the heating transformation is easier, and it is less used as a raw material for brick making.

The appearance of crystalline silica is generally milky white, off-white, light yellow to reddish brown. It has a bright luster, the section is smooth and continuous, with sharp edges and corners, high hardness and strength. In addition to quartz, its mineral composition sometimes contains other small amounts of impurity minerals such as sericite, hematite, and limonite. Mainly distributed in Henan Tiemen, Liaoning Shimen, Shandong Wangcun, Jiangsu Jiangyin, Hunan Xiangxiang, Chongqing, Inner Mongolia Baotou and other places.

The vein quartz is formed by the silica hydrothermal fluid secreted by the underground magma filled in the rock crevices. The appearance is milky white, white, dense and hard, and the crystal is coarse, up to 2mm. , SiO2>99%. Mainly used for quartz glass, high-quality daily ceramic raw materials.

Quartzite is formed by regional metamorphism of quartz sandstone or siliceous rock. Pure quartz is light white, iron-bearing is red, with granite metamorphic structure, high equigranular strength, SiO2 content of 85% to 98% or Higher, mainly used in refractory materials, glass raw materials, metallurgical fluxes, building cornerstones.

Quartz sandstone is a type of mechanical deposition. The rock is composed of debris and cement, the cement is mainly siliceous, chalcedony, opal and so on. The rock section is rough, quartz grains can be seen with the naked eye, the density is poor, and the strength is low.

Generally more than 90%. Pure quartz sandstone is white and off-white, but there are impurities and other colors.

It is mostly used in the manufacture of general silica bricks and glass raw materials.

Flint rock, also known as glass quartz, is a kind of siliceous rock, mainly composed of quartz, chalcedony and opal. Its particles are small, mostly angular, and have high hardness. Generally used for brick making.

Quartz sand is formed by natural transportation of quartzite, quartz sand, vein quartz and the weathered debris of rocks with high silicon content, and deposited in coastal areas and rivers. The surface of quartz particles is smooth, the particle size is uniform, the particle size is between 0.5 and 0.15mm, the texture is pure, white, and the iron content is yellow, light gray or brown, and the composition fluctuates greatly. It is mostly used as glass raw material, building material and siliceous ramming material.


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