As you know, aluminum oxide is not still produced the raw material of metallic aluminium, but also is widely used in numerous areas such as refractory materials, chemical industry, light industry.Adopt processed natural bauxite production Al more in the world now
2O
3, as the A/S of bauxite (Al in the ore
2O
3And SiO
2Weight ratio) 10 when above, generally adopts Bayer process, namely press and boil lixiviation process, and to lean ore, namely the ore of A/S<8~10 generally adopts Bayer-sintering combination method.A/S is the bauxite of 3-5, and China through years of researches and practice, has set up the technological process of production of processing with alkali-lime sinter process.This above-mentioned flow process comprises operations such as the desiliconization of slip preparation, grog sintering, grog stripping, dissolution fluid is made with extra care, the decomposition of refining back solution, Aluminium hydroxide roasting.In the Pulp preparation operation, slip alkali is than (mol ratio) [Na
2O]/([Al
2O
3]+[Fe
2O
3]) be controlled at O.94~O.98, and calcium is than (mol ratio) [CaO]/[SiO
2] be 2.22~2.26, the alumina silica ratio Al of ore pulp
2O
3/ SiO
2(weight ratio) is generally about 4.O.Above-mentioned slip is fired in rotary kiln, 1250 ℃~1300 ℃ of firing temperatures; In grog stripping operation, there is side reaction, i.e. β-2CaO.SiO in the grog
2In process in leaching, decompose the Ca of generation (OH)
2With the Al in the solution
2O
3And SiO
2Water generation reaction fossil garnet causes a part of Al in the solution
2O
3Reenter insoluble solid phase, thereby cause Al
2O
3Loss.In order to control and to reduce above-mentioned side reaction loss, Al in the sodium aluminate solution after the stripping
2O
3Content must be controlled at below 130 grams per liters, so whole technical process has to operate in the low concentration situation, solid circulating rate strengthens.Moreover handled ore grade is low, SiO
2Content is higher, and flow process discharge waste residue amount is big.More than comprehensive, whole flow process energy consumption height, efficient is low, the production cost height.
The objective of the invention is: provide the alkali-lime sinter process technical process of a kind of processing than the bauxite of higher-grade (about A/S 6-12), the solid circulating rate of whole flow process is reduced, the waste residue amount reduces, thereby improves process efficiency, reduces production costs.
The present invention is technology for producing alumina via high alumina to silica ratio sintering process, comprise the operations such as refined liquid decomposition after solution desilicification after slip preparation, clinkersintering, grog stripping, the stripping, the desiliconization, Aluminium hydroxide roasting, main feature is: at the slip preparation process, slip A/S is controlled at 6~12, alkali is than 0.8~1.0, calcium is than 0.8~2.5, and in grog stripping operation, the sodium aluminate solution composition is after the stripping: (grams per liter) Al
2O
3130~250, Na
2O is complete 150~170, Na
2O carbon 5~20, SiO2 5~20, causticization factor alpha k 1.2~1.5.
At above-mentioned slip preparation process, the alkali ratio is preferably 0.9-1.0, and the calcium ratio is preferably 1.2-2.3.
The sodium aluminate solution alumina concentration is preferably the 160-200 grams per liter after the stripping of grog stripping operation, and α k is preferably 1.2-1.3.
Production technology of the present invention is compared with original production process, and the ore unit consumption is by 1.95 tons/ton-Al of former technology
2O
3, be down to 1.50 tons/ton-Al
2O
3Waste residue (red mud) discharge capacity is by 1.7 tons/ton-Al of former technology
2O
3, be down to 0.8 ton/ton-Al
2O
3, reduce the pollution to environment, and greatly reduced the energy consumption of alumina by sintering, improved Business Economic Benefit.
Comment the invention process example as follows below in conjunction with accompanying drawing:
The chemical analysis of used bauxite is (weight %): SiO
26.52, Fe
2O
33.83, Al
2O
369.1 CaO 9.10, Na
2O 0.8, K
2O 0.64, TiO
22.99, other 7.02, ore igloss 13.84%;
The main thing phase composite of used bauxite (weight %): diaspore 79.2, anatase octahedrite 3.0, kaolinite 3.4, quartz 1.2, rhombohedral iron ore 4.0, other are 9.2 years old
Used lime stone (or contain equivalent CaO lime) composition (weight %): SiO
20.84, Fe
2O
30.18, Al
2O
31.1 CaO 54.37, other are 43.51 years old
Burn till with coal chemistry composition (weight %): SiO
242.6, Fe
2O
35.9, Al
2O
331.7 CaO 6.12, other are 13.68 years old
Stripping is with adjusting liquid composition (grams per liter): Na
2O is complete 55.7, Al
2O
342.2, Na
2O carbon 10.32, Na
2The severe 45.34. of O
The slip preparation is to connect bauxite: Wingdale: industrial ground caustic (weight ratio) is 1: 0.26: 0.23 a ratio, adds bauxite, Wingdale, industrial ground caustic in the raw material mill, and allocates evaporation carbon mother liquid 1.56m into by bauxite per ton
3, slip is milled to+120 mesh sieves on residual about 10%.
Above-mentioned slip is delivered to rotary kiln and fired grog, is firing process, firing temperature: 1260--1320 ℃, material was the 0.5-1 hour chamotte kiln residence time.Gained grog composition is (weight %): SiO
25.34, Fe
2O
32.61, Al
2O
345.0 CaO 9.96, Na
2O is effective 27.8, Na
2O sulphur 2.0, SO
33.87, TiO
21.82 other are 1.6 years old.
The grog that burns till carries out stripping with adjusting liquid in the stripping wet-milling, instantly go out operation, about 80-90 ℃ of stripping temperature, dissolution fluid composition (grams per liter): Na
2O is complete 160.9, Al
2O
3206, Na
2O carbon 10.3, SiO
210, Na
2O severe 150.6.
After the grog stripping, red mud separates with filtering equipment, and solution advances desiliconization process and carries out desiliconization, 165-175 ℃ of desiliconization temperature, and 1.0 hours residence time, separate effluxing or fully utilizing processing after the solid (red mud) that obtains washs, liquid is put in order in the washing lotion auxiliary tone.
White residue separates employing filter and leaf filter, the sodium aluminate solution (Al that obtains after the separation
2O
3/ SiO
2About=330) advance the carbon operation break-down, make byproduct, the whole liquid of white residue washing lotion auxiliary tone after the white residue washing.
Sodium aluminate solution divides two sections to carry out carbonating and decompose, and first section rate of decomposition is controlled at 75-85%, and aluminium hydroxide advances the calcining process roasting and obtains the product aluminum oxide behind the separating, washing, and liquid is put in order in the washing lotion auxiliary tone.Carbon mother liquid after one section decomposition and separation continues logical carbonic acid gas and carries out degree of depth carbonating and decompose, rate of decomposition is controlled at about 95%, secondary decomposes the siliceous higher aluminium hydroxide (being called for short thick aluminium hydroxide) that obtains, separate the back and produce aluminium hydroxide with bayer process, roasting obtains the product aluminum oxide then.Secondary decomposes the carbon mother liquid that obtains and prepares burden through evaporating laggard defibrination operation.Product aluminum oxide major impurity content (weight %): SiO
20.031, Fe
2O
30.008, Na
2O 0.39.