CN1673129A - Bayer process red mud matrix improvement technology - Google Patents
Bayer process red mud matrix improvement technology Download PDFInfo
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- CN1673129A CN1673129A CN 200510018271 CN200510018271A CN1673129A CN 1673129 A CN1673129 A CN 1673129A CN 200510018271 CN200510018271 CN 200510018271 CN 200510018271 A CN200510018271 A CN 200510018271A CN 1673129 A CN1673129 A CN 1673129A
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Abstract
The invention provides a method for treating and improving waste residue red mud generated in the production process of aluminum oxide, which adopts fluorgypsum and peat to improve high-alkaline red mud so as to enable the high-alkaline red mud to become 'soil' suitable for direct growth of plants, and the improved red mud can also be used as a foreign soil source for certain acidic solid waste storage yards or stone mountain greening. Indoor and field planting tests show that the improved yard red mud can be used as a growth medium for various plants such as vetiver, chrysanthemum morifolium, albizia julibrissin, bermuda grass and the like, and is applied to slope protection and greening of red mud dam bodies.
Description
The technical field is as follows:
the invention relates to a method for treating waste generated in the production process of aluminum oxide.
Background of the invention is described.
Red mud is waste residue produced in the production process of alumina. The alumina is produced by using alkali (NaOH or Na)2CO3) The alumina ore is treated to convert alumina in the ore to soluble sodium aluminate, and the alumina is refined from a slurry of sodium aluminate. The iron, titanium, silicon and other impurities in the ore form sediments, and the iron content is high, and the sediments are reddish brown, so the red mud is named. In the production of alumina using bauxite ore as raw material, there are two main methods of bayer process and sintering process. Also, the use of both methods simultaneously is called a combined method. Bayer process yields account for about 92% of the total world production. The Bayer process adopts the following steps: the strong base dissolves out the bauxite of high alumina, high iron, boehmite and gibbsite type, and the red mud alumina, iron oxide and alkali content produced are high; the sintering method and the combined method are used for treating indissolvable bauxite of high alumina, high silicon, low iron, diaspore type and kaolinite type (nepheline used in front Su combination), and the red mud produced by the bauxite has high calcium oxide content and low alkali and iron content.
According to the difference of ore grade and production process, 1-2 t of red mud is discharged when one ton of alumina is produced. The total amount of red mud discharged worldwide is about 6000 million t each year. The total amount of red mud discharged by alumina plants in China every year is about 500 million. The disposal of red mud from alumina plants has become a significant environmental and technical problem in the world in the alumina industry. 10% of red mud is piled up in the ocean and 90% is piled up on land in the world. Open-air stockpiling treatment is mostly adopted in China.
The red mud liquid is characterized by high pH value and total alkalinity, and the surrounding environment is harmed if the red mud liquid is not properly treated. Tests show that the salinization effect of the red mud on the soil is long-term, the pH value of the soil is too high, crops cannot grow normally or are burnt by alkali, and in addition, the soil is hardened and even wasted. After the red mud attached liquid enters the water body, the pH value of the water body is higher, the alkalinity is increased, the carbonic acid balance of the natural water body is damaged, the drinking and agricultural irrigation functions of the natural water body are lost when the pollution is serious, and the natural ecological balance of the river is seriously damaged. In the current society where land resources are increasingly tense and environmental protection is increasingly important, the comprehensive utilization of red mud and the ecological restoration of red mud yards are very important.
For a long time, the treatment of the red mud storage yard is mainly used for researching the anti-seepage technology of the storage yard at home and abroad. The reclamation problem of the red mud yard can not be solved almost because the high alkalinity of the red mud makes the plants hard to survive in the red mud directly, and the reclamation is generally carried out abroad by adopting a method of covering the yard with soil with a certain thickness or a seawater neutralization method. The vegetation on the red mud is not precedent in China.
The invention content is as follows:
the invention aims to improve the Bayer process red mud with high alkalinity, high volume weight, low nutrition and low permeability into 'soil' suitable for direct growth of plants, and the improved red mud can also be used as a soil dressing source for certain acidic solid waste storage yards or rocky mountain greening.
1. Basic characteristics of Bayer process red mud
The red mud of the Guangxi branch company (called plain aluminum for short) of the Chinese aluminum industry company is taken as a research object.
(1) Mineral species and chemical composition of red mud
The mineral substances in the red mud constitute the "skeleton" of the red mud. According to the X-ray diffraction analysis of the red mud sample, the minerals of the red mud mainly comprise:
silicon calcium component-Ca3Al2(SiO4)(OH)8，γ-Ca2SIO4Both account for about 40%.
Iron constituent-Fe2O3The FeOOH and the delta-FeOOH account for 25-30%.
Aluminum component-AlO (OH), Al (OH)35-8 percent.
TiO2，CaTiO2About 10%.
CaCO310% of NaAlSiO8About 4 percent.
In addition, a small amount of Na3(Al.Si)12O24SO43H2And O and other minerals.
Analysis shows that the main component of the red mudis water calcium garnet-Ca3Al2(SiO4)(OH)8The structure of the iron-containing alloy is granular, fine and granular, and impurities such as iron, titanium, magnesium and the like are contained. The other main component is hematite, limonite and delta-FeOOH, and then diaspore and a small amount of Al (OH)3Also, CaCO3The content is not much. Rutile TiO 22Contained in AlO (OH), perovskite contained in Ca3Al2(SiO4)(OH)8In (1).
Chemical composition of red mud mineral is Fe2O3、Al2O3、CaO、SiO2、TiO2、Na2O and the like are more. In particular Fe2O3、Al2O3At most, the sum of CaO, CaO and CaO accounts for more than 65% of the total chemical composition, as shown in Table 1.
TABLE 1 Main chemical composition of Red mud (Unit:%)
| Fe2O3 | CaO | Al2O3 | TiO2 | SiO2 | Na2O | K2O | MgO | P2O5 |
| 26.05 | 26.70 | 16.53 | 7.50 | 6.10 | 1.85 | 0.041 | 0.80 | 0.057 |
Therefore, the red mud is a solid industrial waste and is essentially different from common soil.
(2) Particle size composition of red mud
The red mud discharged from the alumina plant has a fine particle size, and the composition of the red mud particles entering the yard is determined by analysis as shown in table 2.
TABLE 2 composition of incoming red mud particles (particlesize: mm) (% of)
| Sand grain 2～0.02 | Powder sand grain 0.02～0.002 | Sticky particle ＜0.002 |
| 27 | 45 | 28 |
Compared with the international soil texture classification table, the physical properties of the red mud are very close to those of silty clay. The content of physical sticky particles is more than 60 percent, the inter-particle pores are small, the air permeability and the water permeability are poor, and the viscosity and the plasticity are strong.
After the red mud is naturally dried in a yard, the red mud particles are slowly consolidated due to the existence of the active calcium oxide in the red mud, so that the particle size of the particles is changed to form a certain aggregate structure. The composition of the size fraction of the dried red mud measured by sieving is shown in table 3.
TABLE 3 composition of particle fraction of dried red mud
Particle size mm 4020-
Percent% 25.52113.515.75.68
Cumulative amount% 25.546.56075.781.389.3
1.25-2.5 0.595- 0.208- 0.105- 0.095- 0.08- ＜0.074
1.25 0.595 0.208 0.105 0.095
0.7 3.4 3.7 1.8 0.6 0.3 0.2
90 93.4 97.1 98.9 99.5 99.8 100
(3) Volume weight of red mud
The dry volume weight of the red mud in the yard is 1.58t/m3The porosity was 54%.
(4) Nutrient and pH value of red mud
The growth medium nutrient is a substance basis necessary for the growth and development of plants. It is a relatively complex factor but is also a factor that is easily changed by man. The pH value is of considerable importance for green plants. It influences the structure of the medium and the existence and effectiveness of nutrients, and determines whether plants can grow normally. Different plants have different requirements on soil acidity and alkalinity, wherein some plants can grow in a wider pH value range, and some plants are extremely sensitive to the change of the acidity and alkalinity. Most plants cannot develop normally at a pH below 3.5 or above 9, whereas normal growth conditions are within a somewhat narrower pH. Most plants are relatively suitable for growing on neutral or near neutral (slightly acidic, slightly alkaline) soils.
The nutrient and pH value of the red mud are shown in the table 4 through field sampling analysis.
TABLE 4 Nutrients and pH values of Red mud
| Total nitrogen ％ | Available phosphorus mg/kg | Effective potassium mg/kg | Water-soluble sodium salt mg/kg | Organic matter ％ | pH value |
| 0.0051 | 9.08 | 129.5 | 1044 | 0.723 | 9.96 |
In conclusion, the red mud is a low-nutrient industrial solid waste with heavy silty, strong alkalinity and almost no plants suitable for the medium. Red mud must be upgraded to make it possible to become a possible plant growth medium.
2. Bayer process red mud matrix improvement technology
(1) Technical measure
Production of red mud alkalinity and alkaline salt (mainly alkali metal or alkali)Carbonates of earth metals) are involved. When the red mud has soluble alkaline salt (such as Na)2CO3，Na2HCO3) In this case, a strong hydrolysis can make it strongly basic (pH>8.5). When the relative amount of Na + ions adsorbed by the colloid reaches a certain degree, substitution hydrolysis can occur, and the colloid is made to be strongly alkaline.
High concentration of Na+The ions have a toxic effect on the plants. Exchangeable Na+The ions disperse the colloid, destroy the structure, and deteriorate the physical condition.
The strong alkalization of the red mud disturbs the normal physiological activities of plant roots (such as protoplasm degeneration, nutrient outflow, enzyme passivation and the like) and influences the absorption of plants to nutrients. Therefore, most plants are not suitable. On weak acid, neutral and weak alkaline soil, general plants can grow normally. On the other hand, different plants in nature often form a relatively fixed long-term adaptation characteristic in the normal soil acidity-alkalinity range, which is an important aspect of soil ecological fertility. In order to make red mud a suitable growth mediator for some plants, the red mud must be subjected to necessary matrix modification. The red mud is improved by reducing the volume weight and the alkalinity.
A. The main technical measure for improving the red mud is to apply a modifier, namely: the high alkaline red mud is improved by adopting fluorgypsum (waste residue of fluoride salt factory in Pinguo county) and peat. The dry weight ratio of the red mud and the fluorgypsum is 8-12.5: 1, and the humidity is 25-35%. Adding peat into the mixture of the redmud and the fluorgypsum, wherein the volume ratio of the peat to the mixture of the red mud and the fluorgypsum is 7-8: 2-3. Uniformly covering the improved red mud matrix on the red mud surface according to the thickness of 20-30 cm, and carrying out vegetation after the matrix is stable and has sufficient moisture.
a. Organic modifier-peat
Peat is formed by incomplete decomposition of plant residues under the conditions of water accumulation and oxygen deficiency in adults. Brown, brown or dark brown, and acidic to neutral reaction. Loose and porous, the void ratio is as high as 70-80%, and the volume weight is only 0.2-0.3g/cm3. Strong water-holding capacity, the water-absorbing capacity can be up to above 3 times of its own weight, but quick-acting nitrogenThe content is very low. The nutrient status of phosphorus and potassium is very different among different types of peat, generally about 0.1-0.5%.
The peat can improve the physical properties of the red mud and also can improve the chemical properties and nutrient conditions of the red mud. Its advantages are high water-holding power, loosening and air permeability, easy insertion of root system, and high buffering power, activity of microbes and nutrients supply.
In the test, Guangxi local peat was used as an organic modifier. The pH value is 4.45, and the contents of organic matters and humic acid are respectively 48.6 percent and 38.6 percent. It is generally crushed to a particle size of less than 20 mm.
b. Inorganic modifier-fluorgypsum
The gypsum can be used for neutralizing the alkalinity of the red mud.
The fluorgypsum is calcium sulfate CaSO4, which is an acidic salt. The application of the fluorgypsum is mainly to replace harmful Na in the alkaline red mud by ions+The ions are replaced and combined with irrigation to be leached. That is, the fluorgypsum can react with soluble salts in the alkaline red mud to generate insoluble salts and neutral salts, so that the alkalinity of the fluorgypsum is reduced:
calcium ions can replace sodium ions bound in soil colloids, so that sodium-clay becomes calcium-clay:
B. process for the preparation of a coating
Turning and pushing the air-dried red mud into pieces with particle size of 10-25 mm by using engineering machinery; air-drying the fluorgypsum, wherein the grain size is 1-15 mm, uniformly mixing and stirring, adding water, continuously stirring, controlling the humidity to be 25-40%, fully mixing, adding peat with the grain size of 0-20 mm, and uniformly mixing according to the volume ratio of red mud, fluorgypsum and peat which is 8: 2-7: 3.
(2) Improved effect
a. The nutrients and pH of the yard red mud are as shown in table 5.
TABLE 5 nutrient and pH of red mud from yard
| Total nitrogen ％ | Available phosphorus mg/kg | Effective potassium mg/kg | Organic matter％ | pH value |
| 0.001～0.01 | 5～10 | 90～160 | 0.3～0.75 | 9.8～11.5 |
b. The nutrients and pH of the modified red mud are shown in table 6.
TABLE 6 nutrient and pH of red mud after modification
| Total nitrogen ％ | Available phosphorus mg/kg | Effective potassium mg/kg | Organic matter％ | pH value |
| 0.65～1.5 | 8～20 | 80～100 | 6～13 | 8～8.5 |
Greenhouse planting test effect
(1) Planting effect of unmodified red mud
In spring sowing, alkaline-resisting grass seeds are sown in the red mud which is not improved, the seeds slowly germinate, the germination rate is only 0-5%, the seeds are watered once in 10-15 days, and the seeds completely die after growing for about three weeks.
(2) Improved planting effect of red mud
In spring sowing, alkali-resistant grass seeds are sown in the improved red mud, the seeds germinate fast, the germination rate reaches 80% -92%, and the seeds grow better and better after being watered once in 10-15 days. For example, the root length of bermudagrass and paspalum natatum is 15-20 cm after 2-3 months of growth, and the plant height on the ground is 15-35 cm. Corresponding to growth in moderately fertile soils.
Indoor and field planting tests show that the improved yard red mud can be used as a growth medium for various plants such as vetiver, chrysanthemum morifolium, albizia julibrissin, bermuda grass and the like, and is applied to slope protection and greening of red mud dam bodies. The same plants are planted on the red mud without improvement and can not survive.
Example (b):
naturally drying 5.0 tons of red mud, mixing 0.5 ton of fluorgypsum, mechanically stirring uniformly, adding water, continuously stirring for 30 minutes to fully mix, controlling the humidity to be 25-35%, after drying in the sun and loosening, manually and uniformly adding 0.4 ton of high-position peat to obtain the red mud soil capable of directly vegetation. Has been applied to the dam vegetation slope protection of the red mud disposal site of Guangxi Pingguo aluminum industry company.
Claims (5)
1. A method for improving a red mud matrix is characterized by comprising the following steps: the fluorgypsum and peat are used for improving the high-alkaline red mud.
2. The red mud substrate improvement method according to claim 1, characterized in that: the dry weight ratio of the red mud and the fluorgypsum is 8-12.5: 1, and the red mud and the fluorgypsum are uniformly mixed under the condition that the humidity is 25-35%.
3. The red mud substrate improvement method according to claim 1, characterized in that: adding peat into the mixture of the red mud and the fluorgypsum, wherein the volume ratio of the mixture to the peat is 7-8: 2-3.
4. The red mud matrix improvement method according to claim 3, characterized in that: the particle size of the peat should be less than 20 mm.
5. The red mud substrate improvement method according to claim 1, characterized in that: uniformly covering the improved red mud matrix on the red mud surface according to the thickness of 20-30 cm, and carrying out vegetation after the matrix is stable and has proper moisture.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101816280A (en) * | 2010-04-21 | 2010-09-01 | 桂林理工大学 | Method for preparing high-quality soil by fermenting Bayer process red mud and molasses alcohol waste liquid |
| CN102409684A (en) * | 2011-08-04 | 2012-04-11 | 中国铝业股份有限公司 | Storage-yard damming method of red mud by mixed self-solidifying dry process |
| CN102671906A (en) * | 2012-05-05 | 2012-09-19 | 段明丰 | Method for processing coal gangue and red mud |
| CN103408204A (en) * | 2013-07-26 | 2013-11-27 | 河南理工大学 | Method for performing dealkalization on Bayer process red mud by using fluorgypsum |
| CN104262059A (en) * | 2014-10-10 | 2015-01-07 | 遵义市贵科科技有限公司 | Method of utilizing electrolytic manganese residue to improve red mud land |
| CN105481538A (en) * | 2015-12-08 | 2016-04-13 | 泉州师范学院 | Environmentally friendly treatment process of red mud |
| CN106034458A (en) * | 2016-06-14 | 2016-10-26 | 中国环境科学研究院 | Method for preventing red mud stacking field from dust and environment pollution |
| CN108070384A (en) * | 2017-12-27 | 2018-05-25 | 大连地拓环境科技有限公司 | It is a kind of using red mud as acidic soil conditioner of matrix and preparation method thereof |
| CN108977203A (en) * | 2018-08-16 | 2018-12-11 | 中国铝业股份有限公司 | A kind of red mud soil renovation agent and its method of administration |
| CN111014266A (en) * | 2019-12-26 | 2020-04-17 | 中国有色金属长沙勘察设计研究院有限公司 | Red mud yard soil improvement method |
| CN113666771A (en) * | 2021-08-24 | 2021-11-19 | 山西大学 | Method for adjusting alkalinity of artificial planting soil of solid waste base by using industrial flue gas |
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- 2005-02-06 CN CN 200510018271 patent/CN1275884C/en active Active
Cited By (14)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101816280A (en) * | 2010-04-21 | 2010-09-01 | 桂林理工大学 | Method for preparing high-quality soil by fermenting Bayer process red mud and molasses alcohol waste liquid |
| CN102409684A (en) * | 2011-08-04 | 2012-04-11 | 中国铝业股份有限公司 | Storage-yard damming method of red mud by mixed self-solidifying dry process |
| CN102409684B (en) * | 2011-08-04 | 2014-08-13 | 中国铝业股份有限公司 | Storage-yard damming method of red mud by mixed self-solidifying dry process |
| CN102671906B (en) * | 2012-05-05 | 2015-03-11 | 段明丰 | Method for processing coal gangue and red mud |
| CN102671906A (en) * | 2012-05-05 | 2012-09-19 | 段明丰 | Method for processing coal gangue and red mud |
| CN103408204A (en) * | 2013-07-26 | 2013-11-27 | 河南理工大学 | Method for performing dealkalization on Bayer process red mud by using fluorgypsum |
| CN104262059A (en) * | 2014-10-10 | 2015-01-07 | 遵义市贵科科技有限公司 | Method of utilizing electrolytic manganese residue to improve red mud land |
| CN105481538A (en) * | 2015-12-08 | 2016-04-13 | 泉州师范学院 | Environmentally friendly treatment process of red mud |
| CN105481538B (en) * | 2015-12-08 | 2020-02-18 | 泉州师范学院 | Environment-friendly treatment process for red mud |
| CN106034458A (en) * | 2016-06-14 | 2016-10-26 | 中国环境科学研究院 | Method for preventing red mud stacking field from dust and environment pollution |
| CN108070384A (en) * | 2017-12-27 | 2018-05-25 | 大连地拓环境科技有限公司 | It is a kind of using red mud as acidic soil conditioner of matrix and preparation method thereof |
| CN108977203A (en) * | 2018-08-16 | 2018-12-11 | 中国铝业股份有限公司 | A kind of red mud soil renovation agent and its method of administration |
| CN111014266A (en) * | 2019-12-26 | 2020-04-17 | 中国有色金属长沙勘察设计研究院有限公司 | Red mud yard soil improvement method |
| CN113666771A (en) * | 2021-08-24 | 2021-11-19 | 山西大学 | Method for adjusting alkalinity of artificial planting soil of solid waste base by using industrial flue gas |
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