Rock phosphate is another mineral used in the manufacture of phosphatic fertilizers. The main occurrence of rock phosphate in India on a workable scale are : lime phosphate septarian nodules in clay beds associated with the Cretaceous rocks. The total recoverable reserves are estimated at 146.95 million tonnes.
Production
The production of rock phosphate started late but it has increased sharply from 2.32 lakh tones (in 1971) to 13.51 lakh tones in 2000-01 exhibiting a 6 times increase over 1971. Table 17.XLV presents trends in the production of rock phosphate during 1971-2003.
Regional Distribution-almost entire production of rock phosphate of the country is obtained from two states of Rajasthan (93.9%) and Madhya Pradesh (16.1%).
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Rajasthan-Rajasthan is the largest producer accounting for 93.9 per cent of the total production of rock phosphate in the country. Here bulk of the production comes from Udaipur (Jhamarkotra, Kanpur, Nemania, Jhameshwar, Lakarwas, Bhila and Berawas areas), Jaisalmer (Birmania and Fatehgarh areas), Chitaurgarh (Jaoda area), and Banswara (Sallopat area) districts.
The Jhamarkotra area near Jhameswar has estimated reserves at 35 million tones of which about 11 million tonnes have phosphate content of 30 per cent or more.
The thickness of veins varies from l to 50 meters. The Birmania deposits lie in a belt stretching from Birmania to Khora with thickness between I to 4 meters, inferred reserves are 4.34 million tones containin 10 to 12% of phosphate down to a depth of 100 along the dip. The beds are highly folded in Kanpur area. The estimated reserves are at 30 million tone with phosphate content between 12 to 18 percent’
Uttaranchal-in 1997-98 Uttar Pradesh produced 10.21 per cent of the total rock phosphate (phosphoresce) of India. Deposits mainly occur Mussorie syncline (Dehradun district), Tehri Garhwal and Pauri Garhwal districts.
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The important areas art at Durmala, Kimoi, Marrara and Chamasari will” estimated reserves of 18 million tons (up to a depth of 100 m). The beds range in thickness from a centimeter to 14.5 m with phosphate content between 20 and 25 per cent. New deposits have been discovered in Nainital and Banda districts.
Himachal Pradesh-Phosphate deposits occur in the Nigali Dhar and Korgai synclines in Sirmaur district; near Darla in Mahesh district and in Rajgarh, Sharun and Pachmunda areas in Solan district. The mineral content ranges from 18 to 26 per cent while the depth of veins varies from 0.9 to 2.1 m in the Nigali Dhar and 2 to 5 m in Korgai areas.
Jammu and Kashmir-Punch, Rajauri, Riasi and Udhampur districts at Sair, Kanthan and Arnas with mineral content between 19 to 25%.
Tamil Nadu-Tiruchchirappalli district (in Uttatur area; area 26 sq. km). The estimated reserves are at 2 million tones up to 15 m depth with phosphate content between 21.14 and 26.50 per cent.
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Madhya Pradesh-the state is the second largest producer of rock phosphate in the country (6.07% in 2002-03). Bulk of the production conies from Jhabua (79.43%), followed by Chhatarpur (19.20%) and Sagar (.36%) districts. In Jhabua district Khatamba and Kelkua areas with phosphate content around 29 per cent and estimated reserves of 7.1 million tones are the main producers.
Trade
Phosphatic minerals are insoluble in water. Hence, these are treated with sulphuric acid to prepare superphosphate which is easily dissolved in water and applied to the soil.
Indigenous production being insufficient India imports large quantity of rock phosphate every year from Jordan, USA, Israel, Senegal, UAR and Tunisia. In 1971 India imported 13.1 lakh tones of rock phosphate, which increased to 22.31 lakh tones in 1993-94. (3) Gypsum
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Gypsum (CaS04.2H20) is a hydrated supplied of calcium. It is a colorless or whitish mineral formed by the action of sulphuric acid, produced by the oxidation of pyritic matter on limestone and marl. It is generally found in the beds of sedimentary rocks like limestone, sandstone and shale. It is also obtained as a byproduct during the manufacture of salt from brines and sea water by the direct solar evaporation process.
Gypsum is mainly used in the manufacture of ammonium sulphate and Portland cement. It is also used in making of plaster of Paris, moulds in ceramic industry, nitrogen chalk, partition blocks, sheets and tiles, plastics, insulating boards and as a filler in paper rubber paint and textile industries.
The recoverable reserves of gypsum in the country are estimated at 238 million tones. Out of this, 3, 34,000 tones are of surgical plaster grade, 39 million tones of fertilizer pottery grade 34.3 million tons of cement paint grades, 6 million tones of soil reclamation grade and the rest is unclassified.
Production
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There has been a wide fluctuation in the production of gypsum in the country. It was 2.07 lakh tones valued at 12.63 lakh rupees in 1951 which rose to 10.89 lakh tones valued at Rs. 12.16 millions in 1971. The production fell down to 9.57 lakh tones in 1981. The current production (2002-03) has been 28.42 lakh tones valued at Rs. 394.04 millions which is slightly less than previous year’s output (1999-00 production being 32.5 lakh tones valued at Rs. 512.04 millions.
Regional Distribution
The entire production of gypsum in India comes from two states of Rajasthan (99.05%) and Jammu and Kashmir (0.95%). Gujarat, Uttar Pradesh and Tamil Nadu are other producers of the mineral.
Rajasthan-Rajasthan with estimated reserves at 105 million tones is the foremost producer of gypsum in the country (99%). Nagaur district is the major producer (36% of the state), followed by Bikaner (31%), Barmer, Jaisalmer, Pali, Jodhpur, Churu and Sri Ganganagar.
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The important fields of Nagaur district are located at Nagaur, Bhadwah, Manglod Khairat, Dhakoria, Bhadana, Malgu and Jodhiasi. Jamsar field (area of 4 sq km and reserves 25 million tonnes) is the largest gypsum producing area of the country. Other important deposits occur near Denyan Dher, Kayam wala Dher, Akhuoar Dher, Tubrawala Dher, Karriser Dher, Kagrawala Dher, Dhirera, Bharru, Kaoni, Naushera, Siasar, Balhar and Lunkarausar.
In Churu district, gypsum deposits occur near Tarananagar; in Jodhpur around Dhakoria; in Jaisalmerdistrict near Hamirwati Nadi, Lakharer, Mohangarh and Dhani; in Jodhpur district near Pokhran; and in Pali district near Khutani.
Tamil Nadu-In Tamil Nadu deposits of gypsum are found in Coimbatore district (near Annuppapatti, Andiyur, Venkatapuram, Pusaripatti etc; reserves being 8 lakh tonnes), Tiruchchirappalli district (near Tappy. Peria Kurukhai and Asur, Nambakkuruchi, Garudamangalam, Sri Kanburand Kerai), and in Ramanathapuram district (at Kokkadi, Avathandi and Kilakkurai). It is also found in the backwater flats of the northern edge of the Pulicat lake near Kottapalem, Kummarapalem, Pandragam, Kudapatra, Mizuru and Venadu.
Jammu and Kashmir-In Jammu and Kashmir, a massive variety of gypsum (alabaster) is found between Ijara and Islamabad north of the Jhelum valley near Bambyar village. It is also found in Uri tahsil of Baramula district.
Gujarat-In Gujarat gypsum occurs in Bhavnagar (Halar), Jamnagar (Gohilwad). Junagadh and Kachchh districts. In Kachchh about 2.1 m tonnes of gypsum has been estimated near Abesar, Umarsar, Karanpur and Palansiva.
Others-Gypsum is also found in Nellore, Adilabad and Guntur districts of Andhra Pradesh; Sirmaur, Kangra and Shimla districts in Himachal Pradesh; Shahdol, Morena and Satna districts of Madhya Pradesh; Kolhapur, district of Maharashtra; Belgaum and Gulbarga district of Karnataka; Medinipur district of West Bengal; Garhwal and Dehradun districts of Uttaranchal; and Jhansi and Hamirpur districts of Uttar Pradesh.
About90% of the production of gypsum from Rajasthan is utilised in the fertilizer factory at Sindri to manufacture ammonium sulphate. Remaining part of the production is used locally in cement industry. Some gypsum is also exported to neighbouring countries like Bangladesh and Nepal. In 1993-94 India exported 14,394 tons of gypsum valued at Rs. 54 lakhs.