Gypsum
This Patent Application is Patent of Addition to the Patent Application no. 572/KOL/2014 u/s 54 of the Indian Patent Act, 1970.
FIELD OF DISCLOSURE
The disclosure relates to Gypsum.
BACKGROUND OF THE DISCLOSURE
Gypsum has been used more and more as a raw material for cement and architectural boards, and a shortage of supply of gypsum containing various other micro nutrients including silicon in the field of agriculture is felt.
Natural gypsum, by-product gypsum from the manufacture of phosphoric acid fertilizer, or synthetic gypsum prepared from waste sulphuric acid and limestone, etc., have been here to fore main sources of the gypsum, and have been used all in a powdery state.
Phospho-gypsum produced as a byproduct from a phosphoric acid plant is of acidic in nature and finds majority of its use only in cement industry as the acidic nature of it is not suitable for all the soils in common and can be applied only in limited quantity to alkaline soil. Its usage In agriculture is limited due to the fact that the phospho-gypsum contains hazardous elements like radio-active substances and heavy metals.
The naturally available mined gypsum, mainly finds its usage is cement industry and its agriculture usage is not really encouraged due to the huge consumption by cement producers in the country and is not usable in agriculture.
Very little efforts have been made till now to utilize the gypsum / calcium sulphate product produced from LD Slag fines which is treated as waste containing mixture of di-calcium silicate, calcite and calcium hydroxide generated from LD process of steel making.
SUMMARY
The disclosure provides a gypsum comprising

Fe2O3: 3.36-7.51, Si02: 3.21-7.04, P205: 0.850-0.517, MgO: 0.600-1.73, MnO: 0.190-0.033, Al2O3:
2.05-0.921, TiO2: 0.330-0.111, Cr2O3: 0.038-0.052, CaS04.2H20 (CaSO4.1/2H20 & CaSO4): 80.19-
87.32 impurities 8.80-19.74 (all in wt.%).
DETAILED DESCRIPTION
Shown in Table 1 Is composition of a gypsum in wt. %.

The purity of the gypsum is of 80 - 92% as CaS04.2H20.
In addition to the constituents already mentioned, the gypsum composition may further comprise other constituents such as boron, copper etc., in traces which are also a micro nutrients to the plants.
The color of the said gypsum is yellow. The yellow can be because it is a combination of calcium sulphate dehydrate (CaSO4.2H20), calcium sulphate hemihydrate (CaSO4.1/2H2O) and calcium sulphate anhydrite (CaSO4)
The pH for the said gypsum is 6.5 to 7.5 hence it can be used for all kinds of soils for agriculture application.

The gypsum composition meets the fertilizer control order specification against the mineral gypsum as given in the Table - 2.


The gypsum composition for Alkali content including both sodium and potassium as Na% & K% is less than 0.10% for each element.
The gypsum composition for trace and heavy metals content means it is non-hazardous and meeting the TCLP norms of phosphor gypsum in its original composition itself as given in the Table -3.

Various gypsum composition have been tried with varying contents of major and minor elements as provided in Table - 4.


The gypsum also exhibits the properties required for use in ceramic industry. Shown in Table 5 is the properties of the Gypsum and the observed values.


ADVANTAGES
The Gypsum have low alkali and low chloride content and can be used as a soil conditioner for salt affected soils as the calcium replaces the sodium and makes the land alkali free when applied.
The Gypsum provides the silicon source to the plants as the yellow gypsum is also a source of silica along with the macro nutrients like calcium, Sulphur.
The Gypsum can be used as a sulphate fertilizer and combining the advantages of micro nutrients like, Iron, Magnesium, Manganese and phosphorus to all kinds of soils and crops.

Claims:
1. A gypsum comprising:
Fe2O3: 3.36-7.51, SiO2: 3.21-7.04, P205: 0.850-0.517, MgO: 0.600-1.73, MnO: 0.190-0.033, Al2O3: 2.05-0.921, TiO2: 0.330-0.111, Cr2O3: 0.038-0.052, CaSO4.2H20(CaSO4.1/2H2O& CaSO4): 80.19-87.32 Impurities 8.80-19.74 (all in wt.%).
2. The gypsum as claimed in claim 1, wherein pH of the gypsum is 6.5 to 7.5.
3. The gypsum as claimed in claim 1, wherein colour of the gypsum is yellow.
4. The gypsum as claimed in claim 1, wherein setting time is 14-17 Min.
5. The gypsum as claimed in claim 1, wherein Dry MOR is 10-12 Kg/cm2.
6. The gypsum as claimed in claim 1, wherein Compressive strength 130-160 Kg/cm2.
7. The gypsum as claimed in claim 1, wherein Water absorption 60-62 %.