Bauxite

Classification：Sedimentary Rock

Aluminum rich sedimentary rocks, a major aluminum ore, exist in the form of hydroxides in aluminum ores, mainly in gibbsite. Also contains iron oxide, ferric hydroxide and clay minerals. It is a weathering product of aluminum bearing rocks.

Bauxite is actually a general term for ore that is made up of gibbsite and gibbsite as the main mineral that can be used in industry. Bauxite is the best raw material for the production of metal aluminum, and the most important application area, which accounts for more than 90% of the total Bauxite output in the world.
The application of Bauxite has two aspects of metal and non metal. It is the best raw material for the production of metal aluminum, and it is also the most important field of application, which accounts for more than 90% of the total output of Bauxite in the world. Bauxite accounts for a small proportion of non-metallic consumption, but its application is very extensive.

Introduction of ore:
The nonmetallic uses of Bauxite are mainly made of refractory materials, abrasives, chemicals and raw materials of high alumina cement. Bauxite accounts for a small proportion of non-metallic consumption, but its application is very extensive. For example, the chemical products can be used in papermaking, purified water, ceramics and petroleum refining with sulphate, three hydrates and aluminum chloride. Active alumina can be used as a catalyst, catalyst carrier and physical adsorbents for decolorization, dehydration, degassing, deacidification, and drying in the chemical, oil refining and pharmaceutical industries. The aluminum chloride produced can be used for organic synthetic applications such as dye, rubber, medicine and oil. The melting point, viscosity and strength of 3% to 5%Al2O3 can be improved in the glass composition. The abrasive material is the main raw material for the advanced grinding wheel and polishing powder, and the refractory material is an indispensable furnace material in the industrial department.
Aluminum is the second most important metal in the world next to steel. In 1995, the world's per capita consumption reached 3.29kg. Because aluminum has the advantages of small specific gravity, good conductivity, good thermal conductivity, easy machining and many other excellent properties, Yu Guomin's economic sectors are widely applied. The largest amount of aluminum in the world is the building, transportation and packaging sector, accounting for more than 60% of the total aluminum consumption. Aluminum is an indispensable raw material for electrical industry, aircraft manufacturing industry, machinery industry and civil appliances.

Main components:
Gibbsite Al (OH) 3 gibbsite is hydrate hydrate of aluminum hydroxide, and it is the main component in Bauxite. The crystal of the trihydrate is very small. The crystals gather together to form a tubercular, bean or soil, usually white, with a glassy glassy, and red if it contains impurities. They are mainly secondary minerals produced after weathering of feldspar and other aluminum minerals. The chemical composition is Al (OH) 3, and the crystal belongs to the monohydrate P21/n space group. It is homogenous with the bayerite and the nordstrandite. The old said gibbsite or water aluminite. It was named after the surname of mineral collector C.G. Gibbs (Gibbs) in 1822. The crystal structure is similar to the brucite, which is made up of the sandwich biscuit (OH) -Al- (OH) coordination eight surface layer, only the Al3+ does not occupy the full space in the interlayer, and only occupies the 2/3. The crystals of gibbsite are generally very small, which are pseudo six square sheets, and often form twins. White, or because of the impurity and was pink to red staining. Glass luster, cleavage surface of pearl luster. The cleavage at the bottom is very complete. The hardness of Moss was 2.5 to 3.5, and the proportion was 2.40. Gibbsite is a secondary product of chemical weathering of aluminous minerals such as feldspar. It is the main mineral component of laterite Bauxite. But it can also be the cause of low temperature hydrothermal solution. Output hydrothermalvein Russia South Ural hereby rato ouse in peace between 5 cm size crystals.

Morphological characteristics:
The theory of Bauxite (Crystal Chemistry) is composed of (wB%):Al2O365.4, H2O34.6. The common isomorphism substitutes have Fe and Ga, Fe2O3 can reach 2%, Ga2O3 can reach 0.006%. In addition, there are often impurities such as CaO, MgO, SiO2 and so on.
Monoclinic system: a0=0.864nm, b0=0.507nm, c0=0.972nm, Z=8. The crystal structure is similar to brucite and belongs to the typical layered structure. The difference is that Al3 only fills the eight surface space of 2/3 in the two layer OH- of the two layer of OH- that is the closest accumulation layer (001), because Al3 has a higher charge than Mg2, so it can balance the charge of OH- with a less Al3 number.
The trapezoid column crystal: C2h-2/m (L2PC). The crystal is a false six square plate, very rare. The main simplex: parallel double sided a, C, m of the trapezoid column. It is usually (100) and (110) bimorph. Common polycrystalline double crystal. The aggregates are radioactive, fibrous, scaly, husk like, bell shaped or oolitic, lenticular, spheric, or fine-grained. It is mainly colloidal amorphous or fine grain.
Physical properties: white or light gray, light green, because of the impurity was light red. Glass luster, cleavage surface pearl luster. Transparent to translucent. The cleavage is absolutely complete. The hardness is 2.5~3.5. Relative density 2.30~2.43. It has a stink of dirt. Under the polarizing mirror, it is colorless. Two axis crystal. Ng=1.587, Nm=Np=1.566.
Occurrence and combination: it is mainly composed of aluminosilicate, which is decomposed and hydrolyzed. The tropical and subtropical climate is conducive to the formation of gibbsite. In regional metamorphism, dehydration can be transformed into boehmite and diaspore (140~200 C). With the increase of metamorphism, it can be transformed into corundum.

Resource characteristics:
The distribution of Bauxite in China is mainly concentrated in large and medium-sized deposits. There are 31 large deposits with reserves greater than 20 million T, and their reserves account for 49% of the total reserves in the country. There are 83 medium-sized deposits of 2000~500 tons of reserves, and their reserves account for 37% of the total reserves in the country, and 86% of the large and medium-sized deposits are in the total.

The quality of China's Bauxite is relatively poor, and the diaspore type ore with difficulty in processing and energy consumption accounts for more than 98% of the total reserves of the country. Of the retained reserves, the first grade ore (Al2O360% to 70%, Al/Si > 12) only accounted for 1.5%, two grade ore (Al2O351% to 71%, Al/Si > 9) accounted for 17%, three grade ore (Al2O362% to 69%, Al/Si > 7) occupied 11.3%, four grade ore (Al2O3>62%, Al/Si > 5) accounted for 1.5%, Al2O3>54%, Al/Si > > ) accounted for 8.3%, seven grade ore (Al2O3>48%, Al/Si = 6) accounted for 1.5%, the rest of the ore grade is unknown.

Another disadvantage factor of China's Bauxite is that there are not many Bauxite deposits suitable for open pit mining. According to statistics, it accounts for only 34% of the total reserves of the country. Unlike foreign red soil Bauxite, Chinese ancient weathering crust type Bauxite is often associated with many minerals. In the Bauxite distribution area, the overlying strata often produce industrial coal seams and high quality limestone. In the ore bearing rock series, there are semi soft clay, hard clay, iron ore and pyrite. Bauxite ore is also associated with gallium, vanadium, lithium, rare earth metals, niobium, tantalum, titanium, scandium and other useful elements. In some areas, the above symbiosis minerals are often combined with Bauxite to form industrial deposits. Gallium, vanadium, scandium and so on in Bauxite also have recycling value.
China's Bauxite has a high degree of geological work. By the end of 1994, China's Bauxite reserves accounted for 32.5% of the exploration stage, and 55.8% of the detailed investigation stage. Both of them accounted for 88.3% of the total reserves in the country.

Discovery process:
Aluminum was found in 1825 by the Danish physicist H.C. Hors de (H.C.Oersted) using the interaction of potassium amalgam and aluminum chloride to obtain aluminum amalgam, and then the mercury was removed by distillation, and metal aluminum was first made. The production of metal aluminum was initially chemical method. In 1854, the French chemical scientist H. H.SainteClaireDiwill (H.SainteClaireDiwill) founded the sodium method and the Russian physicist H.H. H.H.. SW. E, C and B ein E) founded by magnesium chemical method. France started the industrial production by chemical method in 1855. It is the earliest country to produce aluminum in the world. The discovery of Bauxite (1821) was earlier than that of aluminum, which was mistaken for a new mineral at that time. To produce aluminum from Bauxite, we first need to make alumina and then electrolysis to produce aluminum. The exploitation of Bauxite began in France in 1873. The production of alumina from Bauxite began in 1894, and the Bayer process was used to produce more than 1t per day. In 1900, France, Italy and the United States and other countries had a small amount of Bauxite mining, and the annual output was only 90 thousand tons. With the development of modern industry, aluminum is applied to the aviation and military industry as metal and alloy, and then to the civil industry. From then on, the aluminum industry has developed rapidly. By 1950, the production of aluminum and aluminum in the world had reached 1 million 510 thousand tons, and increased to 20 million 920 thousand tons in 1996. It became the second only important metal second only to steel.

The rule of origin:
According to Liao Shifan et al's opinion, the Bauxite deposits in China can be classified into palaeo weathering crust type Bauxite deposits and lateritic Bauxite deposits.
The formation of China's paleo weathering crust Bauxite deposit has gone through three stages. The first stage is the terrestrial stage, which is formed by weathering in the atmosphere to form the residual, slope - accumulated, weathered crust material containing Bauxite minerals, clay minerals and iron oxide minerals, such as the calcium red soil layer, the red soil layer or the red soil Bauxite. This stage is the stage of the original residual accumulation, accumulation or accumulation in the atmosphere, and the second stage. It is the water (or lake water) submerged stage of the rich aluminum calcium laterite layer, the red soil layer or the red soil Bauxite, some are submerged immediately for the sea water (or lake water), and some are submerged in the sea (or lake water) after a certain time of rock formation, and gradually buried underground. After the evolution of the diagenesis of a period of time, the original Bauxite is formed. The third stage is an epigenetic enrichment stage. It is the original Bauxite layer which is raised to the shallow part of the surface of the earth to the surface of the surface of the surface. Because of the transformation of surface water or groundwater, the siliceous leaching and aluminum are enriched, and the rich and industrial value Bauxite deposit is formed. The palaeo weathering crust Bauxite in China is mainly formed in Carboniferous. The formation of this type of Bauxite deposit is related to the palaeo weathering crust of erosion section. In general, the long erosion period, especially the underlying bedrock, is carbonate or basic eruptive rock (such as Xuan Wuyan), which is more easily weathered, and the ore deposits are often rich in ore grade, thick in ore beds and large in size.

As for the lateritic deposit Bauxite, generally considered to be formed from stone weathering aluminiferous rock modern climate conditions. The red soil type Bauxite deposit has only one subclass, which is called the Zhangpu type red soil type Bauxite bed, which is the Bauxite bed formed by the weathering of the Quaternary (quaternary) in the period of the period of the period of the period to the Quaternary. Its reserves are few and only 1.17% of the total reserves of China's Bauxite. The modern Chinese laterite Bauxite is mainly formed in low latitudes, such as Fujian, Hainan and Guangdong. These areas are hot, rainfall and weathered basalt, so they can form a modern red soil Bauxite. Although China's Spratly Islands and the central Sand Islands are also in low latitudes, there is a climate of Bauxite, but these islands rise to land for a long time, only 1~3 million years, weathering time is short, so it is difficult to form a Bauxite deposit.

Genetic classification:
(1) Xiuwen carbonatite, paleo weathering crust, Bauxite Bauxite deposit is also known as carbonatite and paleo weathering crust. The reason is related to the paleo weathering crust of laterite in Karst. Because of the lentil deposit of the Bauxite and the lower carbonate rock base rocks, the Bauxite is not deposited, but is deposited in the laterite weathering crust near the dry lake. This type of ore deposits in Guizhou Xiuwen County Hill Dam Bauxite deposit is a typical. Because the underlying bedrock is the carbonate rock, it is formed by the weathering effect of the residual slope of the rich aluminum calcium laterite. Generally speaking, the longer the erosion time is, the longer the weathering time is, the more and the thicker the aluminum calcium laterite layer is rich in the residual slope formed by weathering, the more Bauxite products are generated, the less clay minerals and the higher the grade of the ore. Rich, the greater the thickness of the ore layer.
(2) the Xin'an type carbonate paleo weathering crust is the original accumulation subtype Bauxite deposit, also known as the carbonate paleo AEO crustal accumulation subtype Bauxite bed, which is more typical of the Bauxite bed in Xin'an Zhang kiln in Henan. The Bauxite of this type of deposit is directly covered with the Karst erosion surface of carbonate rocks. In many cases, the deposits are accumulated in the karst caves and dissolves in Karst. The ore bodies are not long (hundreds of M), but the thickness is larger (40 to 60m). If the erosion time is short, only the calcium laterite residual layer is formed, and the transport phenomenon is slightly migrated. Although the ore quality is slightly poor, the ore layer is stable and the thickness change is small.
(3) Pingguo type carbonate paleo weathering crust site accumulation modern Karst accumulation subtype Bauxite deposit. Also known as carbonate paleo weathering crust in situ accumulation, the modern Karst subtype Bauxite bed. The stratiform ore of this deposit is covered with limestone within the thickness of the underlying bedrock within the thickness of hundreds of meters. After quaternary Karst, the limestone and Bauxite rocks fall into calcite red soil and Bauxite rock fragments to fall into accumulated ore. The formation conditions of this kind of deposits are mainly as follows: a certain scale of stratified ore, suitable climate conditions, thicker limestone in the upper and lower strata, and the thinner clay shale of the floor and the bottom of the floor.
(4) Zunyi type aluminosilicate paleo weathering crust subsurface Bauxite deposit. Also known as the aluminosilicate weathering crust, the subtype Bauxite bed is deposited, the underlying bedrock is fine crumbs or basic volcanic rocks, and is the Bauxite bed of the lateritic weathered crust of the underlying bedrock (a few slope deposits). The metallogenic regularity of this type of deposit is that there is a transitional phenomenon with the underlying bedrock, and there is an erosive cross section with the overlying strata, so the thickness changes and the ore free skylight is more. Secondly, the thickness of the ore layer, the size of the ore body, the ore grade and the rich and the poor depend on the length of the discontinuous time of the erosion and the nature of the underlying bedrock. Easily weathered. If the erosion time is long, the underlying bedrock which is eroded and weathered is mostly fine clastic rock and clay shale, only a part of carbonate rock, often thick, large scale and good ore quality, but no ore window increases. If eroded weathered underlying bedrock is weathered basalt, the ore bed thickness and ore body scale may be larger, and ore may also be richer. If the underlying bedrock is a relatively weathered basalt, the time of erosion and discontinuity is too short, and the weathering effect is not thorough, and the thickness of the ore layer, the size of the ore body and the quality of the ore are difficult to meet the ideal.

Main uses:
Bauxite ores are versatile:
(1)aluminum smelting industry. It is used for national defense, aviation, automobile, electrical appliances, chemical industry, daily necessities, etc.
(2)precision casting. Bauxite clinker is made into fine powder and made into moulds after investment casting. It is used for military industry, aerospace, communication, instrumentation, machinery and Medical Devices Department.
(3)used for refractory products. High bauxite clinker refractory degree up to 1780 degrees, strong chemical stability, good physical properties.
(4) aluminum silicate refractory fiber. It has the advantages of light weight, high temperature resistance, good thermal stability, low thermal conductivity, small heat capacity and mechanical vibration resistance. It is applied to many industries, such as iron and steel, nonferrous metallurgy, electronics, petroleum, chemical industry, aerospace, atomic energy, national defense and so on. It is a high temperature arc furnace with high aluminum clinker into the melting temperature of about 2000~2200 C. It is a white "cotton" - aluminum silicate refractory fiber, which is melted at high temperature, high pressure and high speed air or steam. It can be pressed into fiber blanket, plate or woven fabric instead of refractory bricks lined with industrial high temperature furnace such as smelting, chemical and glass. Firemen can make clothes made of fireproof fabric.
(5) with magnesia and bauxite as raw material, adding appropriate binder, used for pouring ladle lining the whole barrel effect.
(6) all kinds of aluminum compounds can be made from bauxite cement, abrasive materials, ceramic industry and chemical industry.
The most important uses are aluminum metal, refractory and abrasive materials, as well as high alumina cement raw materials. The use of ore is different and its quality is different. The industry standard of Bauxite stone (YS/T78-94) issued by China Nonferrous Metals Industry Corporation in 1994. According to this standard, Bauxite is divided into three types of sedimentary type diaspore, stacked diaspore and laterite trihydrate, and divided into nine grades, such as LK12-70, LK8-65, LK5-60, LK3-53, LK15-60, LK11-55, LK8-50, LK7-50, LK3-40, etc. In addition to the chemical composition of Bauxite, the standard also requires that the water of the diaspore of the sedimentary type of diaspore should not be more than 7%, and the moisture of the accumulative diaspore and the red clay type trihydrate should not be more than 8%. Besides, the particle size of Bauxite stone should not be greater than 150mm. Bauxite stone should not be mixed with dirt and limestone.