鋁礬土簡介：

鋁礬土（aluminous soil；bauxite）又稱礬土或鋁土礦，主要成分是氧化鋁，系含有雜質(zhì)的水合氧化鋁，是一種土狀礦物。白色或灰白色，因含鐵而呈褐黃或淺紅色。密度3.9～4g/cm3，硬度1～3，不透明，質(zhì)脆。極難熔化。不溶于水，能溶于硫酸、氫氧化鈉溶液。主要用于煉鋁，制耐火材料。

耐火材料行業(yè)所稱的鋁礬土通常是指煅燒后Al2O3>=48%、而含F(xiàn)e2O3較低的鋁土礦，高鋁礬土熟料是經(jīng)過煅燒的鋁礬土礦。熟料為灰白淺黃及深灰色，它主要用于高鋁質(zhì)耐火材料，也可用來制作電熔棕剛玉。

鋁礬土劃分級別的標(biāo)準(zhǔn)：

高鋁礬土熟料是按AL2O3含量及Fe2O3、TiO2、Ca O+ Mg O、K2O+Na2O等雜質(zhì)含量和熟料體積密度與吸水等項指標(biāo)來分級的。

鋁礬土的種類、級別：

(1)生礬土，即礬土原礦石(天然沉積巖類)。

(2)熟礬土，將生礬土經(jīng)高溫煅燒后(1200～1700℃)稱為熟礬土。

鋁礬土煅燒后，其物化性能變化如下：

1、外觀由原來的灰、深灰、灰黃、灰白、紅黃等顏色，轉(zhuǎn)變?yōu)榘咨?、米黃色、棕紅色、藍(lán)色，而藍(lán)色隨著含鋁量增高而加深。原來的土狀光澤變?yōu)閯傆窆鉂苫蛴椭鉂?，有時表面出現(xiàn) 輕微的熔化石或裂縫；

2、氧化鋁含量增加11～13%,其他雜質(zhì)增加量微；

3、體積縮小23%左右；

4、燒失量為14.5%左右；

5、由一水型鋁石或一水鋁—高嶺石型，轉(zhuǎn)變?yōu)槿嗽靹傆?、莫來石及少量玻璃相?/span>

6、硬度由原來的1～3增加到8以上；

7、體積密度由原來的2.5g/cm3左右增加至2.8～3g/cm3以上；

8、結(jié)晶水、結(jié)構(gòu)水、附著水全部溢出；

9、結(jié)構(gòu)上由疏、松、軟變?yōu)橹旅軋杂玻?/span>

10、吸水性降低；抗渣性、抗堿性增強；

12.強度增加；

13.滲透性減少；

14.氣化率減少；

15.易揮發(fā)成分、易燃燒成分、土氣味完全消失；

16. 耐火度達到1780℃以上。

(3)熟礬土按煅燒窯爐不同分為：

①豎爐熟礬土(SHAFT KILN BAUXITE)；②轉(zhuǎn)爐熟礬土(ROTARY KILN BAUXITE)；③倒焰窯礬土(ROUND KILN BAUXITE)。

(4)熟礬土按不同用途分為：

①耐火級礬土；②研磨級礬土；③電焊級礬土。

鋁礬土檢驗指標(biāo)：

(1)高鋁礬土(含Al2O385%以上)要求檢驗項目：

Al2O3：耐火級85～87%以上，研磨級86%以上，電焊級87%以上；SiO2：耐火級6～7% 以下，研磨級5～6%以下；Fe2O3：耐火級1.6～2%以下，耐磨級2%以下；TiO2:耐火級3.5～4%以下，研磨級4～4.5%以下；K2O+Na2O+CaO+MgO：耐火級0.5～1%以下，研磨級0.5～1%以下。電焊級礬土有的還要求檢驗磷、硫、錳等項目。

B.D.(體積密度)：耐火級3.10～3.20g/cm3以上，研磨級、電焊級不要求檢驗該項目。

L.O.I(燒失量)：均為0.3%以下。

粒度：按買方要求制定，一般有自然塊、100mm、50mm、25mm、10mm、5mm、3mm、1mm等。

水份：一般0.5～1.5%之間，超過扣重或其它條款。

(2)一般礬土(含Al2O380%以上)要求檢驗項目：

耐火級：不小于Al2O3:80%；Fe2O3:不大于2%；B.D:不小于2.8g/cm3；粒度及水份按買方要求制定。

另外，還有將合同中粒度簽定為細(xì)粉的，一般要求在100～200目之間，通過率85～90%以上 。

(3)鐵礬土要求檢驗項目：

Al2O3:不小于80%；Fe2O3:4～10%；TiO2:不大于4%；SiO2:不大于7%，粒度：按買方要求制定。

(4)生礬土要求檢驗項目：

Al2O3:70～73%；Fe2O3:1.5%左右；TiO2:不大于4%；SiO2:不大于6%；燒失量 :14～15%；K2O+Na2O+CaO+MgO=0.5～1%。

Bauxite introduction:

Bauxite (aluminous soil; bauxite), also known as alumina or bauxite, main ingredients are aluminum oxide, hydrate alumina containing impurities, is an earthy mineral. White or grey, brown yellow or light red by iron. From 4 to 3.9 g/cm3 density, hardness, 1 ~ 3, opaque, very brittle. Very difficult to melt. Insoluble in water, soluble in sulfuric acid, sodium hydroxide solution. Mainly used for aluminium, refractory material.

Bauxite, often referred to as referred to in the refractory industry after calcining Al2O3 > = 48%, and contain low Fe2O3 bauxite, high bauxite cber is after calcined bauxite ore. Cber to pale yellow and dark gray, it is mainly used for high aluminum refractory material, can also be used to make the fused corundum.

Bauxite division level of standard:

High bauxite cber is according to the content of AL2O3 and Fe2O3, TiO2, Ca + Mg O O, K2O + Na2O and other impurity content and cber indicators such as volume density and bibulous to classification.

The types of bauxite, levels:

(1) raw bauxite, alumina original ore (natural sedimentary rock class).

(2) the calcined bauxite, the raw bauxite after high temperature calcination (1200 ~ 1700 ℃) is called the calcined bauxite.

Bauxite after calcining, its physical and chemical properties change as follows:

1, appearance by the original gray, dark gray, and sallowness, gray, red, yellow and other colors, into white, beige, palm red, blue, and blue to deepen as the aluminum content increases. The original earthy lustre into corundum or oily luster, sometimes mild melt fossil or surface crack;

2, 11 ~ 13% alumina content, the addition of other impurities micro;

3, is about 23% smaller;

4, ignition loss about 14.5%;

5, by monohydrate LvShi or aluminum - kaolinite monohydrate, into a synthetic corundum, mullite and a small amount of glass phase;

6, hardness increased from 1 to 3 to 8 or more;

7, with volume density of 2.5 g/cm3 increased to 2.8 ~ 3 g/cm3

8, crystal water, structure water, all attached water overflow;

9, dense structure changed from thin, loose, soft to hard;

10, reduce water imbibition; The slag resistance, alkali resistance enhancement;

12. The strength increase;

13. The permeability decrease;

14. The rate of gasification reduces;

15. Volatile components, easy burning comb, soil smell disappear compleby;

16. Refractoriness reach above 1780 ℃.

(3) calcined bauxite by calcining kiln divided into:

(1) vertical furnace calcined BAUXITE (SHAFT up BAUXITE); (2) converter calcined BAUXITE (ROTARY up BAUXITE); (3) down-draft KILN BAUXITE (ROUND up BAUXITE).

(4) the calcined bauxite according to different purposes as:

1) refractory grade bauxite; (2) grinding grade bauxite; (3) welding grade bauxite.

Bauxite test indicators:

(1) high bauxite (including Al2O385 % above) inspection items:

Al2O3: refractory level above 85 ~ 87%, grinding grade more than 86%, welding level above 87%; SiO2: refractory level 6 ~ 7% lower, grinding level 5 ~ 6% lower; Fe2O3: refractory level below 1.6 ~ 2%, wear-resisting level below 2%; TiO2: refractory level below 3.5 ~ 4%, grinding level 4-4.5% lower; K2O + Na2O + CaO + MgO style: refractory level below 0.5 ~ 1%, ground level of 0.5 ~ 1% lower. Some welding grade bauxite also asked test phosphorus, sulfur, manganese, etc.

B.D. (bulk density) : refractory level above 3.10 ~ 3.20 g/cm3, grinding, welding does not require the inspection of the project.

L.O.I (ignition loss) : are all below 0.3%.

Size: according to the request of the buyer, generally speaking, there are natural block, 100 mm, 50 mm, 25 mm, 10 mm, 5 mm, 3 mm and 1 mm.

Water: generally between 0.5 ~ 1.5%, more than heavy buckle or other terms.

(2) general alumina (including Al2O380 % above) requires inspection items:

Refractory grade: no less than 80% Al2O3:; Fe2O3: no more than 2%; B.D: not less than 2.8 g/cm3; Particle size and moisture bulated according to the requirements of the buyer.

In addition, there are will sign for fine powder particle size in the contract, general requirements between 100 ~ 200 mesh, 85 ~ 90% pass rate.

(3) bauxite required inspection items:

Al2O3: not less than 80%; Fe2O3:4 ~ 10%; TiO2: no more than 4%; SiO2: no more than 7%, the particle size: according to the request of the buyer.

(4) raw bauxite required inspection items: 

Al2O3:70 ~ 73%; Fe2O3:1.5%; TiO2: no more than 4%; SiO2: no more than 6%; Ignition loss: 14-15%; K2O + Na2O + CaO + MgO style = 0.5 ~ 1%.

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