इंटरनेट मानक Disclosure to Promote the Right To Information Whereas the Parliament of India has set out to provide a practical regime of right to information for citizens to secure access to information under the control of public authorities, in order to promote transparency and accountability in the working of every public authority, and whereas the attached publication of the Bureau of Indian Standards is of particular interest to the public, particularly disadvantaged communities and those engaged in the pursuit of education and knowledge, the attached public safety standard is made available to promote the timely dissemination of this information in an accurate manner to the public. “जान1 का अ+धकार, जी1 का अ+धकार” “प0रा1 को छोड न’ 5 तरफ” Mazdoor Kisan Shakti Sangathan Jawaharlal Nehru “The Right to Information, The Right to Live” “Step Out From the Old to the New” IS 12082-2 (2006): Control of Asbestos Emission - Recommendations, Part 2: Milling of Asbestos Ore [CED 53: Cement Matrix Products] “!ान $ एक न’ भारत का +नम-ण” Satyanarayan Gangaram Pitroda ““IInnvveenntt aa NNeeww IInnddiiaa UUssiinngg KKnnoowwlleeddggee”” “!ान एक ऐसा खजाना > जो कभी च0राया नहB जा सकता हहहहै””ै” Bhartṛhari—Nītiśatakam “Knowledge is such a treasure which cannot be stolen” IS 12082 (Part 2) :2006 , *J77%F Gk’&tl*%mFiwr– W@3TQ ‘qPT2 q-a-e”mww$im$f’tl% ( mm’TJpl%PT) Indian Standard CONTROL OF ASBESTOS EMISSION — RECOMMENDATIONS I PART 2 MILLING OF ASBESTOS ORE (First Revision) lCS 13.040.40 i .1 0 BIS 2006 BUREAU OF INDIAN STANDARDS MANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG NEW DELHI 110002 February 2006 Price Group 3 I .— ~--’, , “~.. -———. Cement Matrix Products Sectional Committee, CED 53 FOREWORD This Indian Standard (Part 2) (First Revision) was adopted by the Bureau of Indian Standards, after the draft finalized by the Cement Matrix Products Sectional Committee had been approved by the Civil Engineering Division Council. Inrecent years there has been agrowing awareness that exposure to asbestos can have harmful effects onthehealth of workers. In order to give guidance on how the risk of exposure to wsbestosdust can be prevented, controlled or minimized, itwas felt necessary to laydown some standards regarding safe use of different products containing asbestos, improving conditions in workplaces, preventive measures, protection and supervision of the health of workers, packaging andtransport, disposal ofwaste, etc. This standard laysdown the recommendations forcontrol of emission of airborne asbestos dust during miIIing operation of asbestos ore. In the formulation of the standard, due weightage has been given to international co-ordination among the standards and practices prevailing indifferent countries inaddition to relating itto the practices inthe field inthis country. This has been met by deriving assistance from the following publications: ILO Codes of practice: Safety in the use of asbestos, 1984, published by the International Labour OffIce, Geneva RAJHANS(GS) and BRAGG (GM) Engineering aspects of asbestos dust control. Ann Arbor Science Publishers, USA This revision has incorporated the experience gained inthe past and inputs from Mining Research Cell of Indian Bureau of Mines. It has incorporated/elaborated provisions of conveyance of asbestos containing mineral rocks, filtration through high efficiency filters, which can trap the dust up to 0.4 micron, and dust separation bycyclone discharge into water precipitator tank. Acombination of approaches to control airborne asbestos dusts, including that of thick green barrier trees have been recommended. This standard is one of a series of Indian Standards on safety in handling and use of asbestos. Other standards in the series are as follows: IS No. Title 11450: 1986 Method for determination of airborne asbestos fibre concentration in work environment by light microscopy (membrane filter method) 11451 : 1986 Recommendations for safety and health requirements relating to occupational exposure to asbestos 11767:1986 Recommendations for cleaning of premises and plants using asbestos fibres 11768: 1986 Recommendations for disposal of asbestos waste material \ 769 Guidelines for safe use of products containing asbestos: (Part 1) : 986 Asbestos cement products (Part 2) : 987 Friction materials (Part 3) : 987 Non-cement asbestos products other than friction materials 1 770 Recommendations for control of emission of asbestos dust in premises manufacturing products containing asbestos: (Part 1) :1987 Asbestos cement products (Part 2) :1987 Friction materials (Part 3) :1987 Non-cement asbestos products other than friction materials (Continued on third cover) 1S12082 (Part 2) :2006 Indian Standard CONTROL OF ASBESTOS EMISSION — RECOMMENDATIONS PART 2 MILLING OF ASBESTOS ORE (First Revision) 1 SCOPE stages of crushing to release the fibres, screening to remove the rock particles and dust, suction to carry This standard (Part 2) lays down the recommendations away the fibres, cyclones to separate solids from air for control of airborne asbestos dust emission during solid mix, and subsequent de-dusting, de-gritting, milling operation of asbestos ore. classification, grading, etc, to produce a commercial fibre. Conveying equipment like elevators, screw 2 REFERENCES conveyors, belt conveyors form an essential part of The standards listed below contain provisions, which mechanized milling. Large volumes of air are used to through reference in this text, constitute provisions of convey fibre and fibre rock concentrates as well as for the standard. At the time of publication, the editions de-dusting operations for the purposes of classification indicated werevalid. Allstandardsaresubject torevision and other operations. and parties to agreements based on this standard are encouraged to investigate the possibility ofapplying the The types ofequipment used vary widely, depending on most recent editions of the standard indicated below: trade and brand. But, generally speaking the crushers used are, depending on stage of crushing and circuit [S No. Title used, gyrocentric crushers, jaw crushers, cone crushers, 11450: 1986 Method for determination of airborne impactors hammer milIs, tibrezers, ball mills, edge asbestos fibre concentration in work runner mills, pulverisers, etc. Screens are generally environment by light microscopy gyrocentric but may also be of vibrating type. While (membrane filter method) multi-deck sifters are used in de-dusting operations of 11451 : 1986 Recommendations forsafetyandhealth fibres, trommels are also used in de-dusting of fibre requirements relating to occupational concentrators. Everystageofoperation includingmaterial exposure to asbes t os transfer points and tailing disposal points, involves generation of asbestos dust, and therefore, shall be 11767: 1986 Recommendations for cleaning of handled properly to prevent the release ofasbestos dust premises and plants using asbestos into the working environment. fibres 11768: 1986 Recommendations for disposal of 4.2 The processing operations should be carried out asbestos waste material in closed encasing for reduction of release of dust in 12079: 1987 Recommendations for packaging, work environment. Provision shall be made at all dust transport and storage of asbestos generating points of the mill to collect the dust laden air, which shalIbe filtered through high et%ciency bag 3 OBJECT filters which cantrap the dust ofO.4microns andhaving higher filter efficiency up to 99.9 percent. The objectives of this standard are as follows: a) Toprevent orminimize thepotential forexposure 4.3 The dust generating points are generally toairborne asbestosdustduringmilling operations associated with the following operations: of asbestos ore; and a) Material loading, b) To reduce the probability of release of airborne b) Conveying, asbestos dust into the environment. c) Crushing, 4 GENERAL d) Screening, e) Size reduction, and 4.1 The asbestos fibre is usually found in the form,of veins embedded in rock. It is released by successive o Material transfer, bagging and other operations. I 1S12082(Part 2) :2006 4.3.1 Design principles for material handling system conveyors to conveyors, from conveyors to crushers layouts including transfer points enclosures are: and screens, conveyors to final discharge intobags, etc. a) Exhaust hood to capture dust emission at the These particles remain air-borne and effect the quality source, of the work environment. Dust control at the transfer points canbeachieved byanyone orcombination ofthe b) Duct work to provide a channel for flow of following three approaches: contaminated exhaust air to the dust collection, a) Prevention of dust by minimizing the impact of c) Aircleaner toremove dust from thecontaminated bulk material, attrition and air entertainment, air, and d) A fan to provide necessary exhaust flow rates, b) Dry dust collection, and c) Dust separation using liquid spray. The exhaust hood isacritical part ofanydust collection item. Properly designedhood ensuremaximumeftlciency Transfer points shall also be ‘completely enclosed and of the system, minimum exhaust volume, unrestricted connected to dust extraction system. Figure 5 shows movement of the operator and free flow of material one typical example”of enclosing feeding point ofjaw being processed. Conveyors, screens, sifters, trommels crushers. andelevators shallbecompletely enclosed andconnected todustextraction system.The loading pointsofconveyor A dust separation techniques using liquid can reduce shall be provided with rock boxes, where ore enters air-borne dust, elimina~eair-borne dust orseparate dust along the line of conveyor with reduced velocity on to at its source. The type of system can be classified as: the conveyor and reduces the dust generation. Figures a) Water sprays, and 1,2,’3 and 4 show typical examples of dust extraction systems, includinglocationvfrock box,enclosedGont%yor b) Water sprays with additives. and vibrating screens. These wetdust separation techniques require arelatively lowcapital expenditure, limited maintenance and offer Exhaust fans shall be provided for pneumatically reasonable control. conveying the final dust particles to water precipitators forreduction ofdust from the crusher/pulverizers units. 4.3.3 Wheneverbucketelevatorsareusedfortransporting For effective capture ofthe dust, it is important to have theoretofiberizer,thebucketelevatorshallbecompletely an adequate but not exhaustive volume. Adequate dust enclosed and connected to a dust extractor. collection system shall be provided for all operations. 4.3.4 The feeding point at the bucket elevator shall be 4.3.2 Dustparticles become air-borne duringthe transfer provided with proper suction hood sothat asbestos dust of material, like points from bins to conveyors, from does not become air-borne. m SI CRUSHER TRANSFER POINT FIG. 1 DUSTGENERATINGPOINTSINHANDLINGASBESTOSOREFROMTHECRUSHER 2 1S12082 (Part 2) :2006 FiG.2 CONVEYORBELTENCLOSUREINTHELOADINGREGION(THISARRANGEMENTISINTENDEDFORORE LOADING,ANDIF FIBREWEREBEINGLOADED,THEROCKBox WOULDBEREMOVED) Cl TOTALLYENCLOSED CONVEYOR . ~SCRApER CONvEYOR OR CLEANING BELT RET: LJNBRHT SCRAPER FIG. 3 CONVEYORENCLOSUREFORCONVEYORBELTDIJMPINGORTRANSFER 3 —- 1S 12082 (Part 2) :2006 FIG.4 GYRATORYFIBRESCREENANOROTARYASPJRATOR PILLOW~LOCK “’’’”’1 n-’”” ROTATING PIPEm \ll 4 SWIVEL BEARING ‘“0 SHAFT TO BAG FILTER FEE DER JAW CRUSHER FIG. 5 DUSTCONTROLFORTHEJAWCRUSHER 4 1S12082 (Part 2) :2006 5 BAG HOUSE the asbestos bearing rock is fed directly to the runner machines (edge-runner, crusher or fiberizer), dust :i,, 5:1 Theexhaust airfrom various dust generation points generation is high as compared to the plants having :’ shallbe passed to abag house, preferably preceded by bucketelevator arrangement. Theprocessing plantlayout ,,, a cyclone separator with an air lock, where required. shouldhavecontinuous material flowarrangement inside ,,. the plant to reduce the number of dust generations ,, ,,!!. 5.2 Theairused inaspiration andpneumatic conveying points in the plant and the manual feeding of asbestos offibre, often passirrgthrough cyclone collectors, shall ~II !i bearing material in fast moving machines like edge- ,‘i1\ alsopassthrough the main bag house before itisletout runner,crusher orfiberizer etc,shouldbetotally avoided. ,,, into atmosphere. Ill 7.1.2 Crushing and Screening 5.3 If dampers are used in ducts and pipe-lines, it is $ preferable touserotary dampers (butterfly typedampers) ,1,,1,1 than slide dampers since they provide better sealing. 7.1.2.1 Control ofdustduring orecrushing andscreening shall be by exhaust ventilation to a cyclone and bag house. 5.4 Thefilterbagsoftheunitshallbecleanedperiodically t by mechanical shaking to improve filtering efficiency. 7.1.2,2 Owingtotheirhigherpotentialfordustgeneration, Other means of cleaning such as, reverse jet, pulsejet, vibrating screens and grizzlies shall be in leak-proof etc, also may be used, provided they do not blow fine enclosures withsuitable flexible connections tothe feed dust out due to more vigorous cleaning action, and outlet chutes exhaust vents. 5.5 Fabric filters to be used in bag house as filtering medium shall preferably be made of cotton satin cloth, 7.2 Chutes Itisboth eflicient and durable. Other suitable synthetic Chutes which feed belts, either from other belts or from materials may also be used. other equipment, shall always be closed. While selecting the filter cloth, appropriate air to cloth 7.2.1 Chutes should feed axially, where practicable. ratio shall be considered. Selection of improper filter cloth may lead to ineftlcient running of dust collection 7.2.2 Long vertical drops which cause puffing of dust, system or increase in emission of asbestos dust into shall be avoided. atmosphere. 4 7.2.3 Chute shall be run at angles exceeding the angle 6 GENERAL MAINTENANCE OF CONVEYORS, of repose of the materials to reduce the velocity of the PIPES AND DUCTS materials fed to the conveyor. The ducts and lines used for carrying dust laden air have to be maintained properly to prevent dust leaks 7.2.4 Chutes shall have adequate cross-section and t and withstand wear. The maintenan ce personnel shall shall run at appropriate slopes so that it shall carry be issued his powered lights to locate dust leakage’s required material withoutplugging. Surgefeedconditions when repairs are required. A system of patch marking shall be considered, wherever required. shallbeusedfor locating the leakagepoint. The detected leaksshallberepaired expeditiously. Itisrecommended 7.2.5 Chute enclosures shall be leak-proof and yet to have the system under vacuum so that only allow ready access. in-leakage occur. NOTE—The initiator of a work order shall mark the 7.2.6 Access doors to chutes shall be of leak-proof leakage point with fluorescent patch or other suitable design. identification mark and the maintenance man shall remove the patch identification mark and attach itto the work order 7.2,7 Where ore containing rocks are being conveyed whenrepairsarecompleted. Thepatchoridentification colour shall be changed each week so that outstanding work can be and chutes of bolted construction are used, the joints spotted ataglance shall be fitted with packing. 7 CONTROL OF ASBESTOS EXPOSURE IN 7.2.8 Where only fibre is conveyed, fully welded SPECIFIC ACTIVITY chutes may be used but the same shall be leak-proof. 7.1 Loading, Crushing and Screening 7.3 Conveyors 7.1.1 Material Loading 7.3.1 All conveyors shall be totally enclosed. The asbestos bearing rock feeding is one of the main dust generation activity in a processing plant. Where 7.3.2 Belt width and speed shall beadequate enough to 5