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WO2007009379A1 - Procede pour la reduction de teneur en carbonates dans le chemin d'ecoulement de production d'alumine - Google Patents

Procede pour la reduction de teneur en carbonates dans le chemin d'ecoulement de production d'alumine Download PDF

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Publication number
WO2007009379A1
WO2007009379A1 PCT/CN2006/001745 CN2006001745W WO2007009379A1 WO 2007009379 A1 WO2007009379 A1 WO 2007009379A1 CN 2006001745 W CN2006001745 W CN 2006001745W WO 2007009379 A1 WO2007009379 A1 WO 2007009379A1
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WO
WIPO (PCT)
Prior art keywords
lime
content
alumina
carbonate
alkali
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/CN2006/001745
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English (en)
French (fr)
Inventor
De Chen
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
China Aluminum International Engineering Corp Ltd
Original Assignee
China Aluminum International Engineering Corp Ltd
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Filing date
Publication date
Application filed by China Aluminum International Engineering Corp Ltd filed Critical China Aluminum International Engineering Corp Ltd
Publication of WO2007009379A1 publication Critical patent/WO2007009379A1/zh
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
    • C01F7/00—Compounds of aluminium
    • C01F7/02—Aluminium oxide; Aluminium hydroxide; Aluminates
    • C01F7/04—Preparation of alkali metal aluminates; Aluminium oxide or hydroxide therefrom
    • C01F7/06—Preparation of alkali metal aluminates; Aluminium oxide or hydroxide therefrom by treating aluminous minerals or waste-like raw materials with alkali hydroxide, e.g. leaching of bauxite according to the Bayer process
    • C01F7/0606—Making-up the alkali hydroxide solution from recycled spent liquor
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/10—Process efficiency

Definitions

  • the invention relates to an alumina production process, which is used for a lime burning process in an alumina plant raw material workshop and an alkali replenishing process in an evaporation plant.
  • the sodium carbonate in the process is continuously accumulated. After each Bayer cycle process, the sodium carbonate in the process accumulates a part of the increase, and the increase of the sodium carbonate content has many adverse effects on the production. Therefore, there are salt causticizing processes in production.
  • the function of the salt causticization process is to precipitate sodium carbonate in the evaporation mother liquor from the solution, and convert the sodium carbonate into caustic soda by lime causticization, and recycle the causticized solution back to the process.
  • the sodium carbonate in the process is mainly brought in by the following four routes:
  • Bauxite is brought into C0 2 : Bauxite usually contains a small amount of dolomite and other minerals containing co 2 , and the ore is added to the raw mill to grind, and the co 2 in the ore enters the process.
  • the air contains C0 2 , and the C0 2 is in contact with the sodium aluminate solution for a long time, and a small portion of the NaOH in the sodium aluminate solution is converted into Na 2 C0 3 , so that the C0 2 in the air enters the process.
  • these co 2 into the process are in the form of sodium carbonate in the process of accumulation, resulting in high flow of sodium carbonate, adversely affect the production of alumina.
  • the conversion of caustic soda to Na 2 C0 3 is detrimental to alumina production.
  • Sodium carbonate is an ineffective base that circulates in the process and adversely affects alumina production, such as causing sodium aluminate solution.
  • Increased viscosity, unfavorable for the production of sand-like alumina products, precipitation during the dissolution and evaporation process to form sodium carbonate crucibles, blockage of pipes, valves, adhesion to heat transfer The surface of the device reduces its heat transfer coefficient, affecting the normal operation of the heat exchanger.
  • the co 2 in the process is mainly brought into the production process through four ways, in which the co 2 in the bauxite is determined by the characteristics of the ore itself, and the co 2 in the air is inevitable, in the current technical conditions. Next, these two factors are unchangeable. In fact, these two factors is not much flow into C0 2 is usually only about 30% and ⁇ 02 a greater amount of additional factors into two processes, i.e., a base of lime and complement factors, usually It accounts for about 70%, and these two factors can be improved.
  • the present invention proposes a new process to reduce the concentration of carbonate in the solution.
  • the object of the present invention is to: use a new process to reduce the carbonate content of the process and eliminate the adverse effects of carbonate on the process.
  • the invention is realized by: converting the lime in the alumina furnace to the lime in the rotary kiln, and the C0 2 content in the lime is 2 to 3%; canceling the existing sintering method to the Bayer process , using NaOH > 42% liquid caustic to the base method of the Bayer process.
  • the base of the Bayer process uses the seed system of the sintering system. Because of the high content of impurities such as sodium carbonate and sodium sulfate in the mother liquor of the sintering method, the alkali method will use a large amount of carbon.
  • the acid salt is brought into the Bayer process.
  • the invention converts it into a Bayer process system to supplement the liquid caustic soda by NaOH > 42%, and does not use the sintering method to separate the mother liquor to supplement the alkali, thereby eliminating the influence of the carbonate in the mother liquor of the sintering method on the Bayer system.
  • the beneficial effects of the invention are as follows: the carbonate content in the process is reduced, the adverse effect of the carbonate on the process is eliminated, and the working efficiency of the heat exchanger is improved.
  • Embodiments of the present invention The existing shaft furnace fired lime in the alumina plant is changed into rotary kiln burnt lime, the lime burned in the rotary kiln is good in quality, and the lime content in the co 2 is low; for the combined alumina plant, Bayer The system system uses alkali hydroxide with NaOH > 42%, and does not use the seed system of the sintering system to supplement the alkali. By adopting these two measures, the Co 2 process brings in co 2 Can be greatly reduced.
  • the lime burning process of the alumina plant is currently disposed in the raw material workshop of the alumina plant. From the perspective of environmental protection, the lime burning process can be arranged in the alumina plant by using the rotary kiln to burn lime, or the lime can be fired. The process is arranged in a limestone mine, and the burnt lime is transported into the alumina plant by a car for use in an alumina plant.

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  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Geology (AREA)
  • Inorganic Chemistry (AREA)
  • Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
  • Manufacture And Refinement Of Metals (AREA)

Description

氧化铝生产过程中降低流程中碳酸盐的方法 技术领域：
本发明涉及一种氧化铝生产工艺， 用于氧化铝厂原料车间石灰烧 制工序和蒸发车间补碱工序。
背景技术：
在拜尔法氧化铝生产过程中， 流程中的碳酸钠是不断积累的， 每 经过一个拜尔循环过程， 流程中的碳酸钠就积累增大一部分， 碳酸钠 含量增高对生产造成许多不利影响， 故生产中均设有排盐苛化工序。 排盐苛化工序的作用是将蒸发母液中的碳酸钠从溶液中析出， 并将碳 酸钠用石灰苛化的方法转化为苛性钠， 苛化后的溶液返回流程中循环 使用。
流程中的碳酸钠主要由以下 4条途径带入的：
( 1 )石灰中带入 co2: 用一水硬铝石生产氧化铝， 在原料磨工序 要配入 7 ~ 10%的石灰， 由于石灰中通常含有 3 ~ 4%的 C02， C02随石 灰进入流程。
( 2 )铝土矿带入 C02: 铝土矿中通常含有少量的白云石及其它含 co2的矿物， 矿石加进原料磨中磨矿， 矿石中 co2的随之进入流程中。
( 3 )补碱中带入 C02: 氧化铝生产过滤中需要不断向流程内补充 碱， 无论是补液体苛性碱还是补工业碱粉， 或者是烧结法向拜尔法补 碱， 都要向流程中带进 co2， 液体碱中含 co2少， 故带进流程中的 co2 少些， 而工业碱粉以 Na2C03为主， 则带进的 C02较多， 烧结法溶液中 碳酸盐含量高， 这种补碱方式也会向流程中带入大量碳酸盐。
( 4 ) 空气中含有 C02, 该 C02长期与铝酸钠溶液接触， 会将铝酸 钠溶液中的少部分 NaOH转变成 Na2C03, 从而使空气中 C02进入流程。
由于以上四个方面的原因向流程中带进 co2 , 这些 co2进入流程 后， 均以碳酸钠的形式在流程中积累， 造成流程中碳酸钠偏高， 对氧 化铝生产带来不利影响。
从工艺上来说， 苛性钠转变为 Na2C03对氧化铝生产是不利的， 碳 酸钠是一种无效碱， 它在流程中循环积累， 对氧化铝生产造成不良影 响， 如造成铝酸钠溶液粘度增加、 对生产砂状氧化铝产品不利、 在溶 出、 蒸发过程中析出形成碳酸钠结疤， 堵塞管道、 阀门， 粘附在换热 器表面使其传热系数降低， 影响换热器正常运行等。
经物料平衡计算分析， 流程中 co2主要通过四个途径带进生产流 程， 其中铝土矿中的 co2是矿石本身特点所决定的， 空气中 co2进流 程也不可避免， 在目前技术条件下， 这 2个因素均是不可改变。 实际 上， 这 2个因素带进流程 C02的并不多， 通常只占 30%左右， 而另外 2 个因素带进流程中的 < 02量更大， 即石灰和补碱因素， 通常占 70%左 右， 且这 2个因素是可以改进的。
通过对 co2进流程的分析， 本发明提出新的工艺方法来降低溶液 中碳酸盐的浓度。
发明内容：
本发明的目的在于： 采用新的工艺方法， 降低流程中碳酸盐含量， 消除碳酸盐对流程的不利影响。
本发明是这样实现的： 将氧化铝厂用竖炉烧制石灰改为用回转窑 烧制石灰， 石灰中 C02含量为 2 ~ 3%； 取消现有的烧结法向拜尔法补 碱工艺， 采用 NaOH > 42%的液体苛性碱向拜尔法系统补碱方式。
以往的氧化铝厂全都用竖炉烧制石灰， 竖炉烧制石灰石的分解率 低、 得到的石灰中 <：02含量高， 且活性较差。 采用回转窑取代竖炉烧 制石灰， 石灰石分解率可从 88 ~ 91%提高到 96 ~ 98% , 石灰中 C02含 量从 4 ~ 6°/。降低到 2 ~ 3% , 石灰带入流程中的 C02大幅度减少。
目前， 我国六大氧化铝厂中有五个采用联合法生产工艺。 根据联 合法理论， 拜尔法系统的补碱采用烧结法系统的种分母液， 由于烧结 法种分母液中碳酸钠、 硫酸钠等杂质含量较高， 采用这种补碱方式会 将大量的碳酸盐带进拜尔流程中。 本发明将其改为拜尔法系统自行补 NaOH > 42%的液体苛性碱， 不用烧结法种分母液补碱， 消除了烧结 法种分母液中碳酸盐对拜尔系统的影响。
本发明的有益效果为： 降低了流程中的碳酸盐含量， 消除了碳酸 盐对流程的不利影响， 提高了换热器的工作效率。
具体实施方式：
本发明的实施例： 将氧化铝厂现有的竖炉烧制石灰改为回转窑烧 石灰， 回转窑烧制的石灰质量好， 石灰中含量 co2低； 对于联合法氧 化铝厂， 拜尔法系统补碱采用 NaOH > 42%的液体苛性碱， 不用烧结 法系统的种分母液补碱。通过采用这两项措施，拜尔法流程中带进 co2 的可大幅度减少。
氧化铝厂石灰烧制工序目前均配置在氧化铝厂内原料车间， 从环 保的角度考虑，采用回转窑烧制石灰， 可以将石灰烧制工序配置在氧化 铝厂内， 也可以将石灰烧制工序配置在石灰石矿山， 烧制好的石灰用 汽车运进氧化铝厂， 供氧化铝厂使用。

Claims

权 利 要 求
1.一种氧化铝生产过程中降低流程中碳酸盐的方法， 其特征是： 将氧化铝厂用竖炉烧制石灰改为用回转窑烧制石灰， 石灰中 co2含量 为 2~3%； 采用 NaOH>42%的液体苛性碱向拜尔法系统补碱方式。
PCT/CN2006/001745 2005-07-18 2006-07-18 Procede pour la reduction de teneur en carbonates dans le chemin d'ecoulement de production d'alumine Ceased WO2007009379A1 (fr)

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CN200510200400.8 2005-07-18
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111252790A (zh) * 2020-03-16 2020-06-09 中国铝业股份有限公司 一种拜耳法高碳碱溶液蒸发和析盐工艺改进的方法

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104591242B (zh) * 2015-02-04 2016-02-17 河北科技大学 一种中低品位铝土矿低钙铝比石灰烧结制备熟料的方法

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4451443A (en) * 1982-07-28 1984-05-29 Aluminum Company Of America Causticization method
JPH08175817A (ja) * 1994-12-27 1996-07-09 Sumitomo Chem Co Ltd カルシウムアルミネート水和物およびこれを用いた水酸化アルミニウムの製造方法
CN1389400A (zh) * 2002-07-23 2003-01-08 中国铝业股份有限公司 一种氧化铝生产过程中补碱的方法
CN1405088A (zh) * 2002-11-12 2003-03-26 中国铝业股份有限公司 一种生产氧化铝工艺过程的补碱方法

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4451443A (en) * 1982-07-28 1984-05-29 Aluminum Company Of America Causticization method
JPH08175817A (ja) * 1994-12-27 1996-07-09 Sumitomo Chem Co Ltd カルシウムアルミネート水和物およびこれを用いた水酸化アルミニウムの製造方法
CN1389400A (zh) * 2002-07-23 2003-01-08 中国铝业股份有限公司 一种氧化铝生产过程中补碱的方法
CN1405088A (zh) * 2002-11-12 2003-03-26 中国铝业股份有限公司 一种生产氧化铝工艺过程的补碱方法

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111252790A (zh) * 2020-03-16 2020-06-09 中国铝业股份有限公司 一种拜耳法高碳碱溶液蒸发和析盐工艺改进的方法

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CN1730394A (zh) 2006-02-08

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