PRESENTATION ON THRESHOLD VALUE OF CHEMICAL GRADE LIMESTONE. Tata Chemicals, Mithapur

Transcription

1 PRESENTATION ON THRESHOLD VALUE OF CHEMICAL GRADE LIMESTONE Tata Chemicals, Mithapur 1

2 1.0 Introduction: In India, Soda Ash is manufactured by Adopting Solvay process (synthetic Soda- Ash) Two essential major raw materials Solar Salt and Chemical grade limestone. Natural deposit of Soda Ash are not found in our country. Solar Salt is produced from sea water by natural evaporation and sun drying process Chemical grade Limestone is mined out from captive mines at Porbandar & Devbhumi Dwarka Districts of Gujarat. Chemical Grade Limestone, having cut of grade of CaCO3 > 92%, SiO2 < 4%, R2O3 <2.5%, MgCO3< 1.2%, is only usable for Soda-Ash manufacturing. High Silica, other oxides & MgCO3 Contents are Harmful for Kiln Operation and generate high solid wastes, causes environmental hazards. Vast deposits of chemical grade limestone along the Saurashtra Sea Coast are suitable for Soda Ash manufacturing. Because of the availability of both major raw materials nearby, geographically Soda Ash industries have grown up at Saurashtra region of Gujarat in India. 100% soda ash production in India is from Saurashtra region of Gujarat. 2

3 Uses of Soda Ash: The Soda Ash is the basic inorganic raw material for manufacturing essential components of daily life. It is used in manufacture of :- float glasses, fiber glass, glass for Industrial use. detergents, paper, ceramics, Sodium silicate, dye stuff, medicines, chemicals, bentonite processing, etc. The glass is mainly used for infrastructures and in automobile. The detergents are back bone of FMCG market and used by common man. 3

4 Classification of Limestone: CaCO 3 > 94% SiO 2 <2.5 % MgCO 3 <1.2% R 2 O 3 <2% CaCO 3 > 92% SiO 2 <4 % MgCO 3 <1.2% R 2 O 3 <4% CaCO 3 > 76% SiO 2 < 18% MgCO 3 >1.2% R 2 O 3 > 4% 4

5 Physical Specification of Limestone for Soda - Ash Manufacturing Size Requirement +50 mm to -100 mm 5

6 Physical Specification of limestone for Cement Manufacturing at TCL Utilizes under size/ fines, generated from sizing of chemical gr. Lst. Size requirement > 50 mm 6

7 Limestone occurrences in Gujarat : 7

8 Geology: Lithology Era Soil -Recent Milliolitic Limestone -Pleistocene Gaj Clay (Yellow calcareous clay) -Miocene ~~~~~~~~~~~~~~~-~~~~~Unconformity--~~~~~~~~~~~~~~~~~~~~~~~~~~ Trape or granophyres - Cretaceous to lower Eocene Milliolitic Limestone is one of the most recent deposit of geological ages. It is dull white to cream, buff to brown in colour, fine to medium in grain size, soft to hard in nature. Limestone is horizontally bedded with varying thickness, influenced by topography of the particular area. This kind of limestone is soft and fragile in nature in comparison to limestone found in other geological ages. 8

9 A typical sectional view of Milliolitic limestone deposit of Saurashtra region 9

10 Chemical Grade Limestone Mining at Tata Chemicals Mines 10

11 Soda Ash manufacturing Process: In the solvay process limestone is used initially to calcine in vertical Kiln to produce CO2 gas and Quick Lime. The CO2 is utilized for Soda-Ash manufacturing while Quick lime is utilized to liberate NH3 from ammonium chloride for re-cycle the ammonia as catalyst in the manufacture of Soda Ash. The latter functions chemically as under : 2NH 4 Cl+Ca (OH) 2 CaCl NH 3 + 2H 2 0 2NH 3 + H 2 O + CO 2 (NH 4 ) 2 CO 3 (NH 4 ) 2 CO 3 + H 2 O + CO 2 2NH 4 HCO 3 2NH 4 HCO 3 + NaCl NaHCO 3 + NH 4 Cl 2 NaHCO 3 Na2CO3 + CO 2 + H 2 O Theoretically limestone consumption is approximately Kg per ton of Soda Ash. NaOH is produced by caustisization of Na 2 CO 3 as under: Na 2 CO 3 + Ca (OH) 2 2 NaOH + CaCO 3 11

12 Captive Limestone Reserves & quality Insitu Reserves Number of Leases Lease Hold Area in Hect. Chemical Grade Reserves in million MT Cement Grade Reserves in million MT 24 ~ Insitu Quality Core samples Contains CaCO3 > 94% and Silica < 2.5% Core samples Contains CaCO3 > 92%, Silica < 4% Core samples Contains CaCO3 + MgCO3 < 92% 22% 46% 32% 12

13 Last six month s Kiln Feed - Limestone quality Sample Detail Constitue nts Limit Max. Min. Average Ranavav Moisture Lime Stone SiO Max R2O Max CaCO Max MgCO Max

14 Soda Ash production vs limestone consumption ratio: Financial Year Soda Ash Production Lime Stone consumption (inclusive import limestone) T/T of limestone for Soda Ash ,71,225 15,18, ,98,897 13,73, ,98,400 13,16, ,10,910 13,65, ,16,381 13,86, Quantity in Tonne 14

15 Cement production vs limestone consumption Ratio: Financial Year Cement Production Clay and Lime stone ESF Cake Marl Consumption consumption consumption ,22,524 6,18,639 2,03,765 1,31,815 5,39,924 5,68,795 1,63,281 1,59,319 5,11,703 6,44,333 76,788 1,51,492 5,27,967 6,96,503 49,618 1,07,610 5,15,695 6,14,241 49,301 92,514 Quantity in Tonne 15

16 Mineral Conservation at Tata Chemicals Limestone consumption is least among SA industry T/T. Cut of grade of Limestone is CaCO3 >92%, Silica < 4% Undersize Limestone (-50 mm) is used in captive cement plant which is generated during process of Limestone sizing for Soda Ash. 100% utilization of mine waste. in-house R&D, (Effluent Solid Filtration) ESF technology is developed to recover CaCO3 from effluent discharge of Soad-Ash plant. ESF cakes are utilized in Cement Manufacturing Thus solid waste of Soda-Ash is re-used in Cement manufacturing addressing environmental concern of solid waste disposal and conservation of cement gr. Limestone. 16

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18 INTRODUCTION TO SITE 21

19 Thank You 22