The common structures of bauxite in Henan Province are clastic, oolitic, dense, honeycomb, sandy and earthy. Clastic, oolitic and compact structures are the most common ore structure types of bauxite in western Henan, which are mostly produced in thin ore bodies and upper parts of thick ore bodies with low grade. Honeycomb, sandy and earthy bauxite mostly occurs in the middle and lower part of karst depression, with large thickness and high grade.
1) Debris structure: the debris is mostly subangular and subcircular, with a particle size of 1~5mm and individual10 ~ 20 mm. The debris is composed of fine-grained aphanitic diaspore and a small amount of kaolinite. Poor sorting, often with directional arrangement.
2) Oolitic grain structure: Oolitic grain consists of crystalline and aphanitic diaspore, a small amount of kaolinite and iron. Oolitic particles are spherical, ellipsoid and concentric ring structure, with a diameter of 0.5~2mm. Often contains a small amount of beans, 3 ~ 5 mm in diameter.
3) Dense structure: composed of cryptocrystalline diaspore, more kaolin minerals and a little iron. The mineral particles are fine, difficult to distinguish with naked eyes, delicate in appearance, flat in fracture, clod, and containing a small amount of sand.
4) Honeycomb structure: there are often irregular cavities in the ore, which are similar in size to beans and oolites. It is speculated that the ore has been eroded by surface water for a long time, and some beans, oolites, clay and iron are leached out by weathering. Honeycomb pore size is generally 1~5mm, and some holes are filled with secondary kaolinite.
5) Sand-like structure: Sand and cement are composed of granular and columnar diaspore with a particle size of 0. 1~2mm, and a small amount of kaolinite is distributed between diaspore. Contains a small amount of iron hydroxide. The appearance of ore is fine sandstone, and the boundary between sand and cement is often unclear. Sandy bauxite is the product of intense leaching, in which other substances are basically completely removed and aluminum minerals are highly enriched.
6) Soil-like structure: the ore is mainly composed of fine diaspore, with fine particles in the form of silty sand, brittle structure, and often soil-like, with brick gray and cyan gray as the main colors. Rare, occasionally seen in the depths of private mining pits. During drilling, it is difficult to core because of its brittle structure.
In addition, according to the particle size of minerals, bauxite structure can be subdivided into colloidal particles, fine particles and medium particles. Bauxite ore, which is dominated by colloidal granular minerals, is often dense and massive with a shell-shaped cross section. The mineral particle size is less than 0.005 mm, and the ore composed of fine-grained and medium-grained minerals is generally in the form of soil and sand, with the mineral particle size of 0.005 ~ 0. 1 mm, and the secondary diaspore or anatase in the crystal cave has a coarse particle size of 0.1~ 0.2 mm..
According to the degree of mineral crystallization, bauxite structure can be divided into heteromorphic, semi-automorphic and automorphic structures. In the self-form structure, it can be divided into scale-like, columnar, needle-like and rod-like structures according to its morphology. Scaly minerals include gibbsite, illite and kaolinite. Platelike and short columnar minerals include anatase, anatase, alunite, strontium aluminum phosphate, etc. Columnar and acicular minerals include diaspore, zircon and tourmaline. And rod minerals are represented by halloysite.
Structure of 4.3.3.2 ore
The ore structure of bauxite in Henan Province can be divided into dense massive, breccia-like, thin-layered, directional and semi-directional structures, and soil-like, sand-like, porous and honeycomb structures. Microfluidic structure can be seen under the microscope.
1) dense massive structure: composed of colloid-fine-grained minerals. Generally, clay minerals have a high mass fraction, mainly poor minerals. A small amount of this type of ore is mainly composed of fine diaspore, and the flow structure can be seen under the microscope.
2) Bubble structure: The aluminum claystone deposited in the early stage was not completely weathered, and moved into the nearby new sedimentary area in the form of breccia, forming uneven breccia accumulation.
3) Thin layer structure: Minerals of different colors are arranged orderly along bedding, and some of them form bands and micro-bedding.
4) Directional and semi-directional structures: Oval and lenticular oolites or extended alumina clay fragments in the ore are arranged in parallel along the bedding direction.
5) Soil-like, sand-like, porous and honeycomb structure: This kind of ore is mainly composed of diaspore, which is generally high-grade and high-quality bauxite. Their common feature is high porosity. The earthy ore is composed of acicular diaspore. Sandy ore is composed of coarse columnar, short columnar and granular diaspore, and the particles are in direct contact with each other, showing a particle support structure, so both soil-like and sandy ore are very loose. After weathering and leaching of primary ore, porous and honeycomb ores lose some components, such as iron or clay minerals, forming more pores, thus enriching aluminum and forming rich ores.
6) Pressure solution structure: after the ore body is pressed, a sawtooth pressure solution line appears, diaspore recrystallizes near the pressure solution line, and rutile is enriched near the pressure solution line.