Article On -- Chlor-alkali industry in Bangladesh

The main product of chlor-alkali industries in Bangladesh are -- Caustic soda, Chlorine, Soda Ash, Hydrochloric acid, Liquid Chlorine, Sodium Hypochlorite & Stable Bleaching Powder.

Manufacture of Chlorine and Caustic Soda :

Reactions:

     

Methods of manufacture

1.      Chemical: Lime soda Process

2.      Electrochemical: Chloro Alkali Process

a.      Diaphragm Cell

b.      Mercury Cell process

c.       Membrane cell process

Liquid Chlorine

Chemical Formula: Cl₂

Appearance: Clear amber color

Product Quality: Cl₂ purity 99.5%

Uses:

• Manufacture of various chemical compounds e.g., carbon tetrachloride,

chlorinated lime, PVC, HCl, etc.

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• Water purification, manufacture of metallic chlorides, chlorinated lime,

chlorobenzene, etc.

• Shrink proofing wool, in flame-retardant compounds, manufacture of

trichloroethylene, neoprene etc.

• Processing of meat, fish, vegetables and fruit, in special batteries (with

lithium or zinc).

Sodium Hypochlorite:

Chemical Formula: NaOCl

Product quality: Available Cl2

Appearance: Pale greenish liquid

Uses:

• Disinfection, odor control, specification, bleaching.

• Chlorination of drinking and process water, oil refineries, petroleum

refineries.

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• Textile industry, pulp and paper industry, soap manufacturing, food

processors, wood processing.

• Elimination of slime and algae in swimming pool and boiler water.

Bangladesh demand: 40- 50 TPD.

Hydrochloric acid:

Chemical Formula: HCl

Product quality: 30-32% HCl

Appearance: Colorless or slightly yellow fuming liquid

Uses:

• Metal picking and cleaning, industrial acidifying, boiler scale removal

• Processing of bone in gelatin manufacturing industry, food processing (corn

syrup, sodium glutamate).

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• Manufacture of dyestuff, casein, pharmaceuticals, synthetic rubber,

laboratory reagent etc.

• Effluent treatment and the regeneration of ion-exchange resin in water

treatment.

Bangladesh demand: 150- 200 TPD.

Stable Bleaching Powder:

Chemical Name: chlorinated lime

Chemical Formula: Ca(OCl)Cl

Product quality: 30-32% HCl

Appearance: Dry free flowing dull white powder

Product quality: Available chlorine conc. 35-37% min

Uses:

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• Sewage disposal, odor control, BOD reduction and removal of poisonous

matter.

• Potable water purification, mosquito control, control of epidemic etc.

• Bleaching agent (paper & textile), algaecide, bactericidal and deodorant.

• Elimination of algae and slime in swimming pool, sanitation and general

hygiene.

Bangladesh demand: 100- 150 TPD.

There are many chlor-alkali industries in Bangladesh…

For example:

1.    Samuda chemical complex limited

Plant Description: (Chlor-alkali)

Product: Chlor-Alkali products

Plant Location: Sikirgaon, Gazaria, Munshiganj, Bangladesh.

Plant capacity: 7 chemicals of 195 MT/day.

Main Consumers: Textile, Pulp & Paper, Food and Beverage Industry, Water Treatment Plants and many other industries.

Technology Supported By: Nuberg Engineering Ltd., Carbone Lorraine (France), Asahi Kasei Chemical Corporation (Japan), Bertrams Chemical Plants Ltd (Switzerland).

Products:

Sl. No.	Particulars	Unit	Amount
1.	Caustic Soda	MT/ Day	60.00
2.	Chlorine	MT/ Day	7.00
3.	Stable Bleaching Powder	MT/ Day	16.00
4.	Sodium Hypochlorite	MT/ Day	20.00
5.	Hydrochloric Acid	MT/ Day	100.00
6.	Chlorinated Paraffin Wax	MT/ Day	20.00

2.     ASM Chemical Industries

ASM Chemical Industries is a leading edge Chlor- Alkali manufacturing company, based in Dhaka, Bangladesh with a set up to manufacture and market world class chemicals with outstanding product quality, product development capabilities and outstanding services.

Products:

·        Caustic Soda

·        Chlorine

·        Stable Bleaching Powder

·        Sodium Hypochlorite

·        Hydrochloric Acid

·        Chlorinated Paraffin Wax

Short note on Bleaching powder

Bleaching powder is also called calcium chlorohypochlorite because it is considered as a mixed salt of hydrochloric acid and hypochlorous acid. It is represented as:

Preparation

It is manufactured by the action of chlorine on dry slaked lime, Ca(OH)₂ at 40^oC.

This is the Odling view about its formation. There is another view proposed by Clifford according to which bleaching powder is a mixture of calcium hypochlorite and basic calcium chloride.

The manufacture of bleaching powder is carried out in Beckmann’s plant as follows:

Backmann’s plant --- It consists of a vertical cast-iron tower. The tower is provided with a hopper at the top, two inlets near the base (one for chlorine and other for hot air) and an exit for waste gases near the top.

The tower is fitted with eight shelves at different heights each equipped with rotating rakes. The slaked lime is introduced through the hopper and it comes in contact with chlorine, which slowly moves upwards. Bleaching powder is collected in a barrel at the base. The chlorine used in the manufacture of bleaching powder should be dilute and the temperature should be maintained below 40^oC.

Properties

1. It is a pale yellow powder. It has strong smell of chlorine. It is soluble in water but a clear solution is never formed due to the presence of impurities.

2. On long standing it undergoes auto-oxidation into calcium chlorate and calcium chloride.

3. In the presence of cobalt chloride it looses its oxygen.

4. On account of the formation of nascent oxygen, it shows oxidising and bleaching properties.

5. It loses its chlorine by the action of dilute acids (in excess).

The amount of chlorine obtained from a sample of bleaching powder by treatment with excess of dilute acids or carbon dioxide is called available chlorine. A good sample of bleaching powder contains 35 38% available chlorine.

Uses of Bleaching Powder

It is used

(i) as a disinfectant and germicide especially in the sterilization of drinking water.

(ii) for manufacture of chloroform.

(iii) for making wool unshrinkable.

(iv) as an oxidising agent in industry.

(v) mainly as bleaching agent for cotton, linen and wood pulp.

However, delicate articles like straw, silk, ivory, etc., are not bleached by bleaching powder.