Some Relevant Technical Issues on Consistent Coal Quality Asim Chowdhuri & Dr Kalyan Sen, CFRI, 2003

Approach towards Quality Improvement & Supply of Consistent Quality  Proper QMS  Technological options for Quality enhancement  Modification of Standards  Revision of Coal Categorisation

Existing Quality Monitoring System Manual sampling Wagon top sampling Mechanical sampling Constraints Handling of large sized coal

Quality Monitoring of Coal Less reliable due to higher errors Disputes between supplier & consumer Nation being the ultimate looser Problems of Wagon top sampling Sampling sites Inadequate facility - sampling, preparation & analysis Insufficient time, manpower, etc. Results sampling from top only How it affects final results

Quality Monitoring of Coal Higher Bias leading to disputes High Spillage Frequent Chute choking Rapid wear & Tear High Capital investment & Maintenance costs Problems of Mechanical Sampling (200mm sized coal) Constraints

Proposed Modification in Sampling Procedure Benefits More reliable quality data Less Capital investment Low maintenance cost in case of temporary failure of AMS the advantage would be for switching over to wagon top sampling with better precision than that for higher sized coals Supply of lower size coals (50 mm or below) and inclusion of AMS

Identified Technological Options for Coal Quality Upgradation Globally accepted Options for better economics and less environmental pollution Mine planning Dry deshaling at Pit heads Judicious blending Wet beneficiation

Identified Technological Options for Coal Quality Upgradation Proposed: The degree of washing should be limited to that density of cut at which the final product is free from any particle of ash higher than 50-55%. Of course, this often leads to overall ash content level more or less 34%. Present rider: ash level of 34%

Technology Routes for beneficiation LevelScheme Methodology Ash% reducn Cleans (%) M % over ROM coal IDry benefic. Separation of stone/shale based on differential breakage potentiality 3-4>90Nil IICrushing, screening & coarse coal cleaning Coarse coal (13/30mm) washed & mixed with untreated fines; dewatering screens. < % IIICrushing, screening and total cleaning Coarser fraction washed at optimum efficiency levels: fine coal by Spiral: dewatering >10<603-4%

Proposed Modification of Standards Adoption of ISO (Mechanical Sampling) Adoption of ISO 9931 (for Pulverized Coal) Reaffirmation of IS (Code for F&S) Change in ISO (a new term) Characteristic Ash: The ash of the particles in a closely spaced relative density fraction obtained from Float & Sink analysis

Revision of Coal Categorisation for commercial purpose Categorisation system based on GCV (as recd. Moist. basis) & weightage on the ash A Matrix system with closely spaced GCV & ash value. Coal quality could be assessed by maximum ash value and lowest GCV value that will Remove anomalies of the present system Provide incentive for better quality Ensure consistent quality of a consignment