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GB/T 50530-2022Standard for process design of alumina refinery (English PDF)

氧化铝厂工艺设计标准

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Issued by

Ministry of Housing and Urban-Rural Development of the People's Republic of China; State Administration for Market Regulation

Level / Type

National · Recommended

Issue date

October 31, 2022

Implementation date

February 1, 2023

Scope

GB/T 50530-2022 is the English-translated version of 氧化铝厂工艺设计标准.

GB/T 50530-2022 — 1.0.2 This standard applies to the process design of new, expanded and reconstructed alumina plants that use diaspore type, gibbsite type and mixed type bauxite as raw materials to produce metallurgical grade alumina.

1.0.2 This standard applies to the process design of new, expanded and reconstructed alumina plants that use diaspore type, gibbsite type and mixed type bauxite as raw materials to produce metallurgical grade alumina.

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Document preview — GB/T 50530-2022

National Standard of the People's Republic of China

ICS: 91.040.20
Classification: P 34

Issued by: Ministry of Housing and Urban-Rural Development of the People's Republic of China; State Administration for Market Regulation

1 General Provisions6
2 Terms6
3 Basic Requirements11
4 Raw Materials, Auxiliary Materials and Fuel20
4.1 Raw Materials20
4.2 Auxiliary Materials20
4.3 Fuel21
5 Storage and Transportation of Raw Materials and Fuels and Bauxite Crushing22
5.1 Unloading Facilities22
I Railway Transportation22
II Motor Vehicle Transport24
5.2 Storage Yards for Raw Materials and Fuels24
5.3 Bauxite Crushing26
6 Lime Calcination and Milk of Lime Preparation27
6.1 Lime Calcination27
I Calcination of Lime in Shaft Kilns27
II Calcination of Lime in Rotary Kilns28
6.2 Preparation of Milk of Lime28
7 Slurry Preparation29
7.1 Slurry Grinding29
7.2 Flotation Concentrate Batching30
7.3 Preparation of Raw Material Slurry by the Sintering Process31
I Filtration of Bayer Process Red Mud31
II Alkali Powder Unloading, Storage and Transport, and Stockyard32
III Preparation of Raw Material Slurry33
8 Pre-desilication and Digestion34
8.1 Pre-desilication34
8.2 Digestion Feed Pumps35
8.3 Digestion36
9 Clinker Burning and Crushing38
9.1 Pulverized Coal Preparation38
9.2 Clinker Burning40
9.3 Clinker Crushing42
10 Clinker Leaching43
11 Red Mud Separation, Washing and Filter Pressing44
11.1 Red Mud Separation and Washing44
11.2 Flocculant Preparation45
11.3 Red Mud Discharge46
11.4 Red Mud Filter Pressing47
12 Control Filtration and Pregnant Liquor Cooling48
12.1 Control Filtration48
12.2 Pregnant Liquor Cooling49
13 Desilication of Crude Liquor in the Sintering Process50
13.1 Desilication of Crude Liquor50
13.2 Silica Residue Separation53
14 Decomposition of Sodium Aluminate Solution53
14.1 Seed Precipitation53
14.2 Seed Filtration55
14.3 Carbonation Decomposition56
15 Separation, Washing and Storage of Aluminium Hydroxide57
15.1 Separation and Washing of Aluminium Hydroxide57
15.2 Aluminium Hydroxide Storage Silos58
16 Mother Liquor Evaporation and Caustic Liquor Preparation58
16.1 Mother Liquor Evaporation58
16.2 Separation of crystalline alkali61
16.3 Causticization of crystalline alkali61
16.4 Unloading, Storage and Transport of Liquid Caustic Soda and Dissolution of Solid Caustic Soda62
16.5 Caustic Liquor Blending63
17 Cleaning Facilities64
17.1 Alkali Washing Station64
17.2 Hot Water Station64
17.3 Pickling Station65
18 Calcination of Aluminium Hydroxide and Packaging and Storage of Products66
18.1 Calcination of Aluminium Hydroxide66
18.2 Storage of Alumina67
18.3 Product Packaging and Stacking Storage68

Foreword

In accordance with the requirements of the Notice on Issuing the 2019 Work Plan for the Formulation of Engineering Construction Codes and Standards and Related Work (Jian Biao Han [2019] No. 8) issued by the Ministry of Housing and Urban-Rural Development, the standard drafting group, through extensive investigation and research, careful summarization of practical experience, reference to relevant domestic standards and international experience, and on the basis of widely soliciting opinions, has revised this standard.

The main technical contents of this standard are: general provisions; terms; basic requirements; raw materials, auxiliary materials and fuels; storage and transport of raw materials and fuels and crushing of bauxite; lime burning and lime milk preparation; slurry preparation; pre-desilication and digestion; clinker sintering and crushing; clinker leaching; red mud separation, washing and filter pressing; control filtration and cooling of the pregnant liquor; desilication of the crude liquor in the sintering process; decomposition of sodium aluminate solution; separation, washing and storage of aluminium hydroxide; evaporation of the spent liquor and preparation of the alkali liquor; cleaning facilities; calcination of aluminium hydroxide; and product packaging and stacking.

The main contents of the revision of this standard are as follows:

1. The scope of application has been revised, and provisions applicable to gibbsitic and mixed-type bauxite have been added;

2. The terms have been adjusted;

3. Design requirements have been added for auxiliary materials for alumina production, red mud filtration in the Bayer process, flocculant preparation, red mud discharge, red mud filter pressing, cooling of the pregnant liquor, seed filtration, unloading, storage and transport of liquid caustic soda and the conversion of solid caustic soda into liquid caustic soda, alkali washing stations, hot water stations, and acid washing stations;

4. The content on bauxite ore dressing has been deleted.

This standard is under the administration of the Ministry of Housing and Urban-Rural Development.

Guiyang Aluminium and Magnesium Design and Research Institute Co., Ltd.

Chinalco Shandong Engineering Technology Co., Ltd. Chalco Zhongzhou Aluminum Co., Ltd.

Shanxi Xinfa Chemical Co., Ltd.

Chalco Shanxi New Material Co., Ltd.

Shandong Luyang Energy-Saving Materials Co., Ltd.

Hangzhou Aicosaide Electronic Technology Co., Ltd.

Chief drafting personnel of this standard: Li Zhiguo, Song Zhilin, Zhou Fenglu, Wang Jian, Chen Guohua, Zheng Xubin, Chen Yuguo, Tang Shijian, Qu Zheng, Bai Yingwei, Li Ronghua, Wang Zhi, Guo Qingshan, Fu Yidong, Wang Sugang, Lu Xiaokun, Zhang Fengshuang

Chief examiners of this standard: Yin Zhonglin, Jiang Yuehua, Luo Xianqing, Zhang Liqiang, Wu Hongying, Fan Yingfeng, Huang He, Hao Xiangdong, Wang Penghui, Sha Kechang, Zhang Ting'an

1 General Provisions

1.0.1 This standard is formulated in order to unify the technical requirements for the process design of alumina plants, to promote technical progress, to improve design quality, and to achieve advanced technology, economic rationality, safety and reliability.

1.0.2 This standard is applicable to the process design of newly built, extended and reconstructed alumina plants that produce metallurgical-grade alumina using diasporic, gibbsitic and mixed-type bauxite as raw materials.

1.0.3 In addition to this standard, the process design of alumina plants shall also comply with the provisions of the relevant current national standards.

2 Terms

2.0.1 alumina

A stable oxide of aluminium having a variety of crystal forms, with the molecular formula Al2O3.

2.0.2 aluminium hydroxide

The crystalline substance precipitated by the decomposition of sodium aluminate solution, with the molecular formula Al(OH)3.

2.0.3 smelter grade alumina

The alumina used for the production of metallic aluminium by the fused salt electrolysis process.

2.0.4 bauxite

The general designation for ores in which diaspore, gibbsite or boehmite is the principal mineral, and which are composed of varying quantities of compounds of silicon, iron and titanium together with minor or trace quantities of compounds of other elements.

2.0.5 diaspore

An oxide-hydroxide of aluminium with a density of 3.3g/cm3 to 3.5g/cm3 and a Mohs hardness of 6.5 to 7, belonging to the orthorhombic crystal system, with the molecular formula AlOOH or Al2O3 · H2O.

2.0.6 boehmite

An oxide-hydroxide of aluminium with a density of 3.01g/cm3 to 3.06g/cm3 and a Mohs hardness of 3.5 to 4, belonging to the orthorhombic crystal system, with the molecular formula AlOOH or Al2O3 · H2O.

2.0.7 gibbsite

An oxide-hydroxide of aluminium with a density of 2.35g/cm3 to 2.42g/cm3 and a Mohs hardness of 2.5 to 3.5, belonging to the monoclinic crystal system, with the molecular formula Al(OH)3 or Al2O3 · 3H2O.

2.0.8 mixed bauxite

A gibbsite ore containing a proportion of boehmite, or a diaspore ore containing a proportion of boehmite.

2.0.9 red mud

The residue remaining after the extraction of alumina by the Bayer process or the sintering process.

2.0.10 Bayer process

A production method in which alumina in bauxite is directly leached with caustic alkali liquor to obtain a sodium aluminate solution, and alumina is then produced through dilution and decomposition.

2.0.11 sintering process

An alumina production method in which aluminium-bearing raw materials are batched and calcined so that the alumina contained therein is converted into soluble sodium aluminate.

2.0.12 combination process

A general term for alumina production methods formed by combining the Bayer process and the sintering process in different ways.

2.0.13 serial combination process

An alumina production method in which the red mud obtained after bauxite has been treated by the Bayer process is further treated by the sintering process to recover the alumina and alkali contained therein.

2.0.14 parallel combination process

An alumina production method in which high-grade bauxite is treated by the Bayer process and low-grade bauxite is treated by the sintering process, and the sodium aluminate solution produced by the sintering process is used to make up the alkali loss of the Bayer process.

2.0.15 mixed combination process

An alumina production method in which the red mud obtained after bauxite has been treated by the Bayer process is batched with an appropriate amount of bauxite and then treated by the sintering process.

2.0.16 test liquor

The alkali liquor used in alumina production for return to batching.

2.0.17 bauxite slurry

The slurry prepared in accordance with the production process requirements and used for Bayer process digestion.

2.0.18 raw slurry

The slurry prepared in accordance with the production process requirements and used for sintering clinker.

2.0.19 alkali red mud

The Bayer process red mud slurry to which alkali powder has been added in combination process production.

2.0.20 digestion

The process of leaching alumina from bauxite with caustic alkali liquor at the digestion temperature.

2.0.21 total available alumina

Alumina that can be dissolved from bauxite into the solution under specified digestion conditions.

2.0.22 reactive silica

Silica in bauxite that reacts with alkali under specified digestion conditions, causing losses of alumina and sodium oxide.

2.0.23 single-stream digestion

A digestion technique in which the circulating caustic liquor and the raw ore slurry are heated together.

2.0.24 dual-stream digestion

A digestion technique in which the greater part of the circulating caustic liquor is heated separately and a small part is used for preparing the raw ore slurry, the two streams being combined when entering the digester.

2.0.25 pre-desilication

The process in which, before the raw ore slurry enters the digestion heating equipment, the reactive silica is made to react with alkali and be converted into hydrated sodium aluminosilicate or hydrogarnet.

2.0.26 molar ratio

The molar ratio of caustic sodium oxide to alumina in a sodium aluminate solution.

2.0.27 sintering

The process in which the raw material slurry is calcined at high temperature to become aluminate sinter.

2.0.28 sinter leaching

The process of dissolving the useful constituents in the sinter with water or dilute alkali solution.

2.0.29 pregnant liquor

The sodium aluminate solution obtained after the red mud has been separated from the digestion slurry.

2.0.30 desilication

The desilication process in which the silica in the pregnant liquor is converted into compounds of very low solubility and precipitated out as solids.

2.0.31 sodium aluminate solution

The solution containing sodium ions and aluminate ions formed from the alumina hydrates in bauxite under the action of caustic liquor, and from the solid-phase sodium aluminate in the sinter under the action of water or dilute alkali liquor.

2.0.32 control filtration

The filtration process for purifying the suspended solids in the sodium aluminate solution before seed precipitation.

2.0.33 green liquor

Refined sodium aluminate solution in which the solid suspended matter content after controlled filtration complies with the technical requirements for precipitation.

2.0.34 seed precipitation

The process of adding seed crystals to a sodium aluminate solution and lowering the temperature so as to precipitate aluminium hydroxide.

2.0.35 carbonation precipitation

The process of passing carbon dioxide gas into a sodium aluminate solution so as to neutralize the caustic alkali in the solution and precipitate aluminium hydroxide.

2.0.36 one-stage precipitation

A seed precipitation process in which seed crystals are added and the growth of the seed crystals predominates.

2.0.37 two-stage precipitation

A seed precipitation process in which fine seed crystals and coarse seed crystals are added separately, and in which agglomeration of the fine seed crystals and growth of the coarse seed crystals predominate.

2.0.38 spent liquor

The sodium aluminate solution remaining after aluminium hydroxide has been precipitated by seed precipitation or carbonation precipitation.

2.0.39 spent liquor evaporation

The process of heating the spent liquor to its boiling point so as to evaporate the water contained in it.

2.0.40 strong liquor

Spent liquor that has been concentrated by evaporation.

2.0.41 test liquor preparation

The process of mixing and preparing alkali solutions of different concentrations in accordance with the requirements of the circulating alkali liquor for caustic alkali concentration and molar ratio.

2.0.42 caustic cleaning

The process of using heated caustic alkali liquor to clean the scale formed on the surfaces of equipment, piping, filter cloths and the like.

2.0.43 hot water washing

The process of using hot water to clean the alkali, organic matter or salts adhering to the surfaces of equipment, piping, filter cloths and the like.

2.0.44 chemical cleaning

The process of cleaning, by means of dilute sulfuric acid or dilute nitric acid, the scale formed on the surfaces of equipment, pipelines, etc.

2.0.45 mechanical cleaning

The process of cleaning, by means of a high-pressure water pump, the scale formed on the surfaces of equipment, pipelines, etc.

2.0.46 aluminium hydroxide calcination

The process of drying and dehydrating aluminium hydroxide by heating and converting it into aluminium oxide of different crystal forms.

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This preview omits tables, figures, formulas and parts of the technical clauses. The complete document — 144 pages — is available in the English PDF.

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