International Journal of Research and Innovation in Applied Science (IJRIAS) | Volume V, Issue IV, April 2020|ISSN 2454-6194 www.rsisinternational.org Page 143 Granite Slurry: A Valued By-Product as Fertilizer Mohammed Azam Khan 1 , Haritabh Rana 2 1 Manager, Business Development and Quality Control, Fastwell Dealcom Private Limited, Bengaluru, India 2 Assistant Geologist, Geological Survey of India, Kolkata, India Abstract: India accounts for more than 20 % of the granite deposits of the world. Rock dust or granite slurry is a granite manufacturing waste product resulting due to the cutting and polishing process. Large quantities of rock dust are produced annually. Disposal of this rock dust has become a major problem. Granites are enriched in several alkali and alkaline earth elements such as potassium, aluminium, calcium and several trace elements. The authors have tried to find out the suitability of rock dust to its use as a fertiliser. The granite slurry is having good percentage of potassium and nitrogen with alkaline pH values which can be considered good for fertilizer use rather than keeping it as waste. Keywords: Granite slurry, potassium, fertiliser, nitrogen, rock dust I. INTRODUCTION ranite slurry or rock dust is a known waste product during M-Sand manufacturing. Because of the generation of large volume of slurry, the production companies pose a serious problem in disposal of this waste product. Granites being hard and tough and its easy availability make it a household name for widespread use as a construction stone throughout the world. India is highly rich in granite which has been considered as miner mineral but it is a major contributor in foreign exchange earnings. India is the second largest exporter of unprocessed granite after China while ahead of Brazil and South Africa [1]. In India, Granite mines are spread in its different States having production shares as Karnataka (25%), Jharkhand (24%), Rajasthan (23%), Andhra Pradesh (6%), Madhya Pradesh (5%) and Orissa (5%). The granite industry of Karnataka gives a significant percentage of the national and international production leading to approximately 20 % of world’s market [2]. In the last few decades, the granite processing industry has been expanded to a large number, leading to increase in volume of granite slurry production. Disposal of these granite fines is one of the major environmental hazards [3]. Nitrogen, potassium and phosphorous are the three main plant nutrients, out of which potassium and phosphorous are exclusively sourced from geological materials [4], [5], [6]. The processing of natural stone starts from the quarry where boulders are crushed till the final product is achieved. From quarry (rocks) to final product (granite M-Sand), it involves two major processing setups, first in quarry while second in Manufacturing Unit. In quarry, controlled blasting is done using neo-gel, minor explosives and electronic detonators. Ammonia (ANFO) is also used to get the maximum yield from blast. After blasting, boulders are reduced to a size of 500 mm before feeding it to the manufacturing unit. In manufacturing unit, the raw material goes through 4 different stages. Jaw crusher reducing the size from 500 mm to 20 mm. Cone crusher reduces the size from 20 mm to 5mm. Vertical Shaft impactor (VSI) shapes the particle from angular to sub- rounded to smooth the edges by particle to particle impact in order to acquire the desired shape of the particles. Finally, the product is washed to remove the excess quantity of finer particles (below 150 microns) to make the product adhere the standards given by Bureau of Indian Standards (BIS). These removed particles (by-product) then get separated from water by using certain chemicals (Floculants) which segregates water (95% for recycling) and slurry (below 150 micron particles) from each other. This thick slurry is then transported through pipes to a pond shaped area (with a non-porous base) where remaining water content gets evaporated. Even though after drying the powder (dried slurry) is not hazardous but its dispersal with wind may affect the environment of nearby areas, making it an area of interest for the disposal of slurry by using it in agricultural land to maximize the yield of crops. Previous studies [7], [8], [9], [10], [11], [12] have provided evidences that the granite fine particles can act as a source of nutrients to enrich the quality of soil. In this contribution, the authors have tried to find out that can slurry be used to balance the pH of soil in the nearby areas and also acting as an additive resource for macro and micro nutrients. II .MATERIALS AND METHODS The granite samples were collected from the mines of Makenakhalli Village, nearby Bengaluru Rural District, Karnataka, India. The Sample size ranges upto 500 mm which further goes through various crushing stages resulting into both coarse aggregate (20 mm and down, 12.5 mm and down) and fine aggregate (4.75 mm and down) material were analysed. An attempt has been made to analyse both physical and chemical characteristics of the aggregate material. The major focus of the present study lies on particle size of 150 microns and below. Electrical conductivity, pH, major element concentration, macro nutrients, micro nutrients, secondary nutrients and heavy metal concentrations of particles size below 150 micron were analysed. The authors have tried to explore the possibility of using the granite dust as fertiliser comparing it with the various crops and the amount of nutrients used by various plats. III. RESULTS AND DISCUSSION The granite powders analyzed in the present study presented a fine texture, containing nil clay lumps, showing that the G