Magnesium Chemicals From Industrial Waste Dust And Fines

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Conventionally magnesium salts are produced from magnesite bearing minerals such as natural kieserite langbeinite, brucite, seawater concentrates, natural brines, magnesite and dolomite. In the conventional commercial process of production magnesite sulphate, magnesium minerals are decomposed by heating to magnesium oxide, sulphate dioxide is absorbed in the slurry of magnesium at 50-60o in presence of catalyst. In an another conventional method, the magnesium sulphate is produced by the method of double decomposition of gypsum and magnesium carbonate.


The Product is used by tea garden & refractory industries for making special quality refracatories and also the demand is growing in steel, chemicals and pharmaceutical industries.


In this process WASTE DUST generated during the manufacture of magnesite refractories, contains 40-50% - MgO; 2-3% - CaO; 3-4% Fe2O3 and 8-10% SiO2 at 60-80 mesh, it is neutralized with sulphuric acid in a stirred tank reactor under controlled condition. This is followed by vacuum crystallization under meticulously maintained condition, due to numerous meta stable phases and slow equilibrium adjustment to achieve acceptable MgSO4. 7H2O. By operating at controlled temperatures, approaching the maximum practical limit, the dissolved impurities would limit their reaction, provided a large excess of residual acid is not present. The mother liquor from the centrifuge after separating crystal of MgSO4. 7H2O can be utilized for producing magnesium carbonate as end product, by reacting with Sodium Carbonate. This will give sodium sulphate as by product.

Advantages of Indian technologies

  • The invention uses the industrial wastes materials as raw material and it thus minimizes the waste generation.
  • The process helps to produce valuable chemicals, which can serve as the starting material for the other magnesium chemical.
  • Environmentally friendly and free of any waste generation.
  • No need of extensive purification to recover MgSO4. 7H2O.

Plant Parameters

Capacity 1500 TPA
No.of Shifts per day 2
Working days per Year. 300
Land Area, m2 5000
Covered Area, m2 2000


Managerial 2
Skilled 2
Unskilled 2

Raw Material (Tonne per Tonne of Product)

Magnesium Dust, 8 Tons
Sulphuric Acid 2 Tons
Sodium Carbonate 2 Tons

Utilities (Per Tonne of product)

Power 100 KWH
Water 2 Tons

Plant & Machinery

Grinder Reactor
Filter Ejector
Crystallizer Repulper

For further information please contact

National Research Development Corporation
( A Government of India Enterprise )
20-22, Zamroodhpur Community Center
Kailash Colony Extension
New Delhi 110 048. India
Tel: 91-11-26419904, 26417821, 26480767, 26432627
Fax: 011-26231877, 26460506, 26478010