Guidelines for silica sand mining and silica washing plants

Guidelines for Silica Sand Mining and Washing plants CENTRAL POLLUTION CONTROL BOARD (Ministry of Environment, Forest & Climate Change) ‘Parivesh Bhawan’, East Arjun Nagar, Delhi- 110 0321. Background Hon’ble NGT has passed Order dated 29.11.2024 in Original Application No. 203/2021, Devidas Khatri Versus Union of India & Ors. for preparation of guidelines in respect of silica sand mining and silica washing plants. The operative part of the order is as follows: - ”(vii) CPCB is directed to prepare detailed Guidelines in respect of silica sand mining and silica washing plants, to be followed and observed by the concerned Statutory Regulators while granting permission/consent under Water Act, 1974 and Air Act, 1981 and NOC under the provisions of EP Act, 1986 for silica sand mining and silica sand washing plants. CPCB shall look into this aspect of the matter and prepare detailed Guidelines and circulate the same to all concerned, PAN India, within three months.” 2. Legislation w.r.t Minor Minerals Ministry of Mines vide Notification S.O. 423(E) dated 10.02.2015, “In exercise of the powers conferred by clause (e) of section 3 of the Mines and Minerals (Development and Regulation) Act, 1957 (67 of 1957), the Central Government hereby declares quartz, quartzite and silica sand minerals to be minor minerals in addition to the minerals already declared as minor minerals by earlier notification’’. "Minor minerals" means building stones, gravel, ordinary clay, ordinary sand other than sand used for prescribed purposes and any other mineral which the Central Government has declared from time to time or may declare, by notification in the Official Gazette, to be a minor mineral, under clause (e) of Section 3 of the Mines and Minerals (Regulation and Development) Act, 1957 (Act 67 of 1957). Further, four minor minerals namely Barytes, Felspar, Mica and Quartz earlier notified vide Notification S.O 423(E), dated 10.02.2015 are omitted from the list of minor minerals through Notification No. S.O. 924(E) dated 20.02.2025. 3. Brief about Silica Sand, Distribution & Usage 3.1 Brief about Silica Sand Page 2 of 13Silica sand refers to sand having composition and grain-size distribution required for industrial applications. Quartz or silicon dioxide (SiO ) is one of the most 2 common minerals found on the Earth’s surface and it is found in rocks like granite, gneiss, and sandstone. Silica (SiO ) occurs in the form of quartz (crystalline), agate, 2 flint (cryptocrystalline) and opal(hydrous). Sandstone widely occurring in sedimentary deposit while quartzite is the metamorphosed derivative of sandstone. Silica sand is the trade name of the weathered and stone or quartzite. Industrial silica sand is a higher value product than sand and gravel used in the construction activity. Silica sand is an assemblage of individual silica grains in the size range upto 2 mm. A sand can be formed in nature by natural weathering of sandstone and quartzite or mechanically by crushing sandstone/quartzite. Silica mineral comprising quartz, silica sand and quartzite are most abundant available mineral on earth’s crust. 3.2 Distribution Silica sand resources are distributed in Andhra Pradesh, Bihar, Gujarat, Haryana, Karnataka, Madhya Pradesh, Maharashtra, Rajasthan, Uttarakhand, West Begal and Uttar Pradesh States of India. Major mines of silica sand are in Prayagraj District of Uttar Pradesh. The Shankargarh area of Prayagraj District is famous for its Silica mines and for the quality of silica deposits. These mines are situated in the Vindhyan Hills of the Prayagraj District. 3.3 Usage Silica sands have large number of industrial uses depending on their characteristics such as:  Production of glass  Foundry sand  Ceramics  Sandblasting and other abrasives  Building products Page 3 of 13 Filler and extender  Production of silicon and silicon carbide  Pigments  Hydraulic fracturing and propping in the oil industry  Ultra-high silica products in the electronic and fibre optic industries, fused silica, silicone products  Water filtration  Glass and Glass fibre  Silicon carbide,  Hydraulic fracturing,  Foundry sand,  Sodium silicate,  Sand blasting and sand paper,  Filter medium water treatment,  Silicon alloys & metals While quartz crystal finds its use largely in electronics for its piezo-electric properties. 4. Mining and Beneficiation Process The process of Beneficiation of Silica sand involves 04 process i.e. 4.1. Mining 4.2. Crushing 4.3.Washing 4.4. Drying These processes along-with Management Practices are detailed in the following sections. 4.1 Mining (including Management Practices) 4.1.1 Mining Silica: Most of the silica sand deposits are derived manually by opencast method using tools like pickaxes, crow-bars, hammers and shovels. Drilling and blasting Page 4 of 13are also carried out only when hard formations is encountered. While very few mines are semi-mechanised and heavy mining machinery (example: hydraulic excavators/backhoes) are deployed for removal of overburden and ore. Quartz: Deposits are derived manually by simple open cast method, by making pits in the area using pickaxes, crowbar, hammers and chisel. Drilling and blasting are carried out when hard formation in the over burden is encountered. Limitation on mining in coastal zones: Government of India issued a notification u/s 3(1), 3 (2)(v) of E(P)A 1986 and Rule 5(3)(d) of E(P) Rules 1986, which has put limitations on mining activities within Coastal Regulation Zones (CRZ). 4.1.2 Management Practices 4.1.2.1 Environmental Issues Land Deterioration: Land degradation is one of the significant impacts of mining activity which is mainly in the form of alteration of land structure due to excavation, interference with natural drainage, ground water depletion, stacking of mine waste, loss of fertile top soil, degradation of forest land, adverse effect on aquatic biodiversity and public health. Due to unaccounted large scale open cast mining, the land is losing its productivity due to removal of top soil. Fast vegetation cover loss leads to erosion of top soil. Loss of Biodiversity: Natural vegetation play a key role in balancing the local ecosystem and fast green cover loss has adversely affects the eco-balance of the region. Pollution: The Particulate Matter (PM) generated from silica mining, poses threat to the local environment. These particles get accumulated on leaves and thus disturb the photosynthesis and respiration process. Further they may pose health hazard to the surrounding population residing in the nearby villages. The rain water ponded in unfilled mines percolates downward thereby may contaminate the ground water. Surface run-off of muddy water changes the nature of external water bodies and may causes water borne diseases. Page 5 of 13Deterioration of Ground Water and Natural Drainage System: Due to mining activity, ground water may deplete in the area. Due to surface run-off, accumulation of mud, silt and sand in the natural channels, the natural drainage system is adversely affected. 4.1.2.2 Measures to minimize the impact of pollution Dust Control i. Dust is generated from unpaved roads, loading and unloading of materials in trucks, crushing, and drilling operations. These dust emissions may be minimized by spraying water and calcium chloride or other approved/acceptable fugitive dust control compound on roads and stockpiles. Applications of dust suppressants should be done as often as necessary to meet all applicable emission limits. ii. Dust shall be stopped by sprinkling of water on stack and mining bench. The water requirement may be met from the working pit where ground water gets collected. iii. The mining lease holder shall install stationary as well as anti-smog guns to suppress the dust in the mining area as well as on the approach road as an additional support arrangement to suppress the dust generated during loading/unloading and movement of vehicles. iv. Establishment for conducting monitoring of the PM and PM parameters 10 2.5 at site. v. Fugitive emissions from stone quarrying, rock crushing, and screening operations shall not exceed norms as prescribed by the authority. vi. All vehicles carrying raw material should be covered during transportation. vii. All roads should be paved and swept regularly. viii. Any material spillage on roads shall be cleaned up immediately. 4.1.2.3 General Management Practices i. Forestation and afforestation programme shall be implemented in the mining areas to increases the green cover. Page 6 of 13ii. Development of green belt (~5 to 7 m). iii. Land Backfill Programme should be carried out through Reclamation and Restoration Programme. iv. Top soil at site and its management. v. DGPS (Differential Global Positioning System) survey of Mining lease area to be done. Boundary pillars or the mining plane to be erected properly. vi. Fencing of the mining area to avoid illegal mining and to minimise the environmental loss. Also, peripheral fencing of the excavated area to be done. vii. No displacement of fauna due to mining activity shall be envisaged. viii. Provision of distribution of personal protective gears such as dust masks, gloves, ear muffs and helmets to the mine workers. ix. Rotation of workers exposed to dusty and noisy areas. x. Regular medical examinations of workers’ lungs, ears and eyes shall be done. xi. Disaster and emergency planning shall be done beforehand. xii. Mining shall not be done during rains and there shall be construction of retaining walls to prevent surface runoff. xiii. The mining would be restricted to unsaturated zone only above the phreatic water table and will not intersect the ground water table at any point of time. xiv. The mining operation will not be carried out in safety zone of any bridge or embankment or in an eco-fragile zone such as the habitat of any wild fauna. xv. Mining should be carried out as per approved mining plan as well as environment management plan. 4.2 Crushing (including Management Practices) 4.2.1 Crushing The crushing unit should comply with the regulatory norms as prescribed under the E(P) Rules, 2016 as well as the guidelines for stone crushing units issued by Central Pollution Control Board (July 2023) may be referred for compliance as the process involves crushing of sandstone/quartz with the potential of dust pollution. Page 7 of 134.2.2 Management Practices i. Forestation and afforestation programme shall be implemented for increases the green cover. ii. Establishment for conducting/monitoring of the PM and PM parameters at 10 2.5 site at regular interval. iii. All provisions for control of fugitive emission should be made with system for regular operation and maintenance. iv. Provision of distribution of personal protective gears such as dust masks, gloves, ear muffs and helmets to the workers. v. Rotation of workers exposed to dusty and noisy areas. vi. Regular health check-up of the worker should carry out. Regular medical examinations of lungs, ears and eyes shall be done. 4.3 Washing (including Management Practices) 4.3.1 Washing Washing plant is a key process in production of Silica sand. This facility is designed for removal of impurities and any contaminants from silica sand, which affect the quality. 4.3.1.1. Technique for Silica sand washing At present, 04 techniques are available for Silica sand washing: 1) Scrubbing: This technique is used to remove clay and other impurities from surface of sand particles. 2) Washing: This technique involves washing sand with water to remove any remaining impurities. 3) Rinsing: This technique involves rinsing the sand with clean water to remove any remaining washing agents. 4) Dewatering: This technique involves removing excess water from the washed sand to produce a dry product. The following three types of washing plants are available for silica sand washing Page 8 of 13namely; - 1. Manual pit washing Plant 2. Semi mechanised Plant 3. Fully automatic Plant 4.3.1.2 Water requirement for Silica sand washing Water is used for making slurry of raw materials for removal of impurities such as clay. The requirement of water depends upon the percentage of impurities present in the raw materials. In India, raw materials contain about 05- 20 percent impurities. Water is mainly required for washing and some amount of water is required for sprinkling for minimising the fugitive emission. Washing cycle depends upon percentage of impurities present in raw silica ore. Water requirement based on percentage of impurities is given below: S. No. % of impurities Washing Cycle Water Requirement (approx.) 1. 03-05 01 03 times of raw materials 2. 06-10 02 06 times of raw materials 3. More than 10 03 09 times of raw materials About 12-15 % of water loss occurs during washing process. Hence, silica sand washing plant require about 12-15% of additional water depends on seasons/topography/operational scale. The remaining water requirement meet through recycling of washing water through suitable settling units. The water required for the processing of the silica sand shall be accounted either by installing water meters or other suitable alternatives. 4.3.2 Management Practices 4.3.2.1 Environmental Issues in Silica Sand Washing Dust/fugitive emission during washing operation The material handling is a major source of dust emissions. Various handling areas such as loading, unloading, feeders, belt conveyors, screw conveyors, screens etc. are used. Water Pollution during Washing Operation Page 9 of 13As washing operation involve use of water, it causes water pollution. During washing process, washed water is collected and recycled back in process through proper settling units discharge into nearby land, may cause water pollution in nearby areas. Noise Pollution Semi mechanized and fully automatic washing plant involves several washing units, which may create noise. Hence, washing units may be kept in cover with adequate acoustic measures so as to minimize noise pollution. 4.3.2.2 Measures to minimize the impact of pollution i. Dust is generated mainly during feeding of Raw materials and unpaved roads, loading and unloading of materials/Product etc. These dust emissions shall be minimized by spraying water on roads, installing water sprinklers at all source of fugitive emissions and covered conveyor & transfer points. ii. All roads should be paved and swept. iii. Any material spillage on roads shall be cleaned up immediately. iv. To control dust emission, fencing shall be provided around the perimeter of the crusher unit with metal sheets. v. Unit shall ensure that all trucks, tractors used in transportation of silica should be covered to prevent dust emission. vi. Unit shall develop dense green belt in periphery for minimising the impact in surrounding areas. vii. Necessary permission from ground water extraction should be obtained by the unit and it shall comply CGWA guideline for extraction of Ground Water. Unit shall install Rain Water Harvesting system. viii. Unit shall install magnetic flow meter on all borewells/all fresh water intake points for the measurement of water extraction. ix. Unit shall reuse the recycled water through settling tanks and ensure zero liquid discharge. x. The unit shall keep and maintain the record of water usage, source, waste generation, waste stored, waste utilized, etc. Page 10 of 13xi. Clay and rejected siliceous sand generated after the beneficiation process shall be utilized for embankments in mines, stemming material for the blasting, filling of low laying areas, foundations, village roads and brick making. The same may be available to the end users at free of cost. xii. Establishment for conducting/monitoring of the PM and PM parameters 10 2.5 at site at regular interval. xiii. Locations for fugitive monitoring shall be monitored downwind as per the following: Area Location Mine face/benches Drilling, excavation, operational benches Haul road Haul road to processing area Crushing Crushing area, screen and transfer point Ore storage Stock bin/pile area, loading area Waste dump Reject dump 4.3.2.3 General Management Practices i. Forestation and afforestation programme shall be implemented for increases the green cover. ii. The project proponent shall mandatorily provide personal protective equipment i.e. nose mask, gloves, goggles, gumboots to all workers to ensure occupational safety. iii. Rotation of workers exposed to dusty and noisy areas. iv. Regular medical examinations of worker’s lungs, ears and eyes shall be done. 4.4. Drying 4.4.1 Drying Silica sand after washing process consist of approx. 10 % moisture, which requires drying before packing. Drying process carried out by sun dry or forced dryer to reduce moisture content by 0-4%. The major fuel used for forced drying are commercial LPG, LDO etc. 4.4.2 Management Practices Page 11 of 134.4.2.1 Environmental Issues in Silica Sand Drying Fugitive emissions occur during drying process in loading, unloading, feeding, packaging etc. Gaseous emission also occurs due to use of LDO and other fuel. 4.4.2.2 Measures to minimize the impact of pollution i. To control fugitive emissions during drying process, adequate pollution control system such as covered shed, automatic loading, unloading and packaging section should be provided. All potential area should be connected with suction system equipped with appropriate Air Pollution Control Device and stack. ii. Source emission due to burning of fuel should be vented through adequate stack height. iii. Efforts shall be made for post mining restoration of land with native species afforestation. iv. The mud residue generated after silica washing, which contains fine silica particles, must be mandatorily reused for refilling mined pits. Page 12 of 13References:  Quartz and Silica Sand; Bulletin No. 25, Indian Bureau of Mines, Ministry of Mines.  Indian Minerals Yearbook 2022, Minerals Reviews- Volume-III, Ministry of Mines, Government of India.  Mines and Minerals (Development and Regulation) Act, 1957 (67 of 1957) as amended on 10th February, 2015 Ministry of Mines, Government of India.  Mineral Conservation Development Rules 2017  Ministry of Environment, Forest and Climate Change, 9 May 2016, Ensuring sustainable sand mining for sustainable development.  Regulating small-scale mining of minor minerals, A Comprehensive Framework beyond Environmental clearances; Centre for Science and Environment.  https://www.sbmchina.com/media/articals/silica-sand-washing-plant html.  https://www.lzzgmachine.com/ore-washing-plant/silica-sand-washing- plant-process.html. Page 13 of 13