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BARITE (ALSO BARYTES)

Barite ( also Barytes)

Barite or barite has the chemical composition BaSO₄. It has the unique distinction of having high specific gravity of 4.5, being insoluble in water and remaining comparatively unaffected by acids. Its principal use is as a weighting agent in the preparation of drilling mud. It is also found useful in the manufacture of barium chemicals and white paints. To a user extent it is used in the glass and explosive industries and as filler in rubber, leather, textile and paper goods. Barite needs to be pulverized before use in the above industries.

Specifications of barite vary according to its use in different industries. These are discussed below:

(1) Chemical Industry: The BIS (IS: 2881 – 1984) has prescribed specification for chemical industry and oil well drilling as given below:

S. No.	Characteristics	Requirement Grade-I Grade - II Quality A Quality B
i	Insoluble minus silica percent by mass	97	90	90
ii	Silica (as SiO₂) percent by mass	2.0	6.0*	--
iii	Aluminium a (as Al) percent by mass (max.)	0.10	--	--
iv	Iron (as Fe) percent by mass (max.)	0.10	1.5	--
v	Calcium and magnesium (as CaCO₃) percent by mass (max.)	0.10	2.0	--
vi	Fineness (determined by wet method). (a) Passing through 75-micron IS Sieve, (b) Passing through 53 micron IS Sieve, percent by mass (max.)	-- --	-- --	97 90 + 5
vii	Relative Density at 27^o / 27^o C (min.)	--	--	4.15**
viii	Matter Soluble in water percent by mass (max.)	--	--	0.02
ix	Performance	--	--	to pass test
* Silica and aluminium oxide together shall be 6.0 percent ** For off-short drilling the value shall be 4.20

Grade I Suitable for chemical industry. The material under grade-I shall be of two qualities namely quality (A) and Quality (B)

2. Oil Well Drilling: Grade II indicated in the above table shall be suitable for petroleum industry and oil well drilling operations.

3. Pigments for paints: The BIS has standardized specification for both natural barite and precipitated barite (IS: 64 – 1972). The nature barite is the Type – I of the BIS that has been further subdivided in to Grade – I and Grade - II. The Precipitated barite is the Type – 2 of BIS. In this, the desirable parameters are BaSO₄, high oil absorption, fine particle size and white to snow white color. The objectionable parameters are NaCO₃, volatile matter, water solubility, etc. The specification is as follows:

		Type - I (Natural) Grade - 1% Grade - 2%		Type - II (Precipitated) %
i	BaSO₄	95	95	97
ii	BaCO₃ max.	2.24	2.24	0.45
iii	Volatile matter mad.	0.5	.05	0.5
iv	Residue on sieve max.	Residue on sieve max. IS sieve (400 mesh)	0.25 on 63 micron IS sieve (240 mesh	0.1 on 40 Micron IS sieve (400 mesh)
v	Oil absorption	6 to 12		15 to 30
vi	Particle shape	Characteristics of material and similar to that of approved sample.
vii	Color	A close math to that of approval sample.
viii	Matter soluble in water	0.5	--	--
ix	pH of aqueous extract	6 to 8		--
x	Relative density (Sp. Gr. At 25^o C)	4.45		3.36

(4) Robber Industry: Barite containing a minimum 99.5% BaSO₄ is usually preferred. Such purity is not found in nature. Hence leached barite is usually preferred for this; the BIS standardized the specification (IS: 1683 – 1973). In this, water solubility, moisture content, manganese, copper and iron are objectionable, while color, size, density and pH values also play important roles. The specification of bleached barite is as follows:

i	Color	Close match to the approved sample.
ii	Sieve residue: (a) Through 75 micron IS Sieve (b) Through 150 micron IS Sieve	0.4% max. 0.01% max.
iii	Relative density 27^o C	4.2 to 4.5
iv	pH	6 to 8
v	Moisture content	0.5%
vi	Matter soluble in water	0.5% max.
vii	Mn	0.005% satisfies requirement of test
viii	Cu	to satisfy requirement of test
ix	Fe	to satisfy requirement of test

For other industries such as explosive, glass, leather textile, paper, etc., there is no BIS specification at present and the concerned industries have their own criteria of acceptability.

During the preparation and updating of the inventory of barite as on 01.01.1985, it was found of the exploration agencies by and large lay emphasis on three parameters, namely, BaSO₄, specific gravity and color which apparently are easier for them to determined and report. In a large number of cases, however, one or the other of these parameters was not reported by the exploration agencies for the purpose of preparation of inventory. Keeping in view the limitations of the reported data, the following basis was adopted for the purpose of classifying the reserves.

i	Chemical – ‘A’	BaSO₄: +97% either off color or information on color not available
ii	Chemical – ‘B’	BaSO₄: +90% specific gravity either less than 4.75 or information not available.
iii	Oil well drilling	BaSO₄: +90% specific gravity 4.15 (min.)
iv	Paint	BaSO₄: +95% Color – snow white to white.
v	Low-grade	BaSO₄: < 90%

The exploration agencies can give board end use classification of reserves according to BaSO₄ content, Sp. Gravity and color of the mineral, and recommended of the following classification keeping in view the limitation of the exploration agencies.

i	Chemical – ‘A’	BaSO₄: 97%, SiO₂: 2%, Fe: 0.1% Color: off color
ii	Chemical – ‘B’	BaSO₄: +90% specific gravity: less than 4.15 (min.)
iii	Oil well drilling	BaSO₄: 90%, SiO₂ + Al₂O₃ = 6%, CaCO₃ = 2%, Fe: 1.5%
iv	Paint	BaSO₄: +95% Color – snow white to white.
v	Low-grade	BaSO₄: < 90%

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