In defence of coal washing
The decision to abandon the beneficial practice of coal washing by concerned authorities in India is based on unjust perceptions and defamation that must be debunked
The Coal Preparation Society of India is the Indian chapter of the ICPC (International Coal Preparation Congress) and is involved in promoting coal washing as an essential step to coal preparation in order to bring in internationally accepted practices to the Indian coal industry.
There are several difficulties in expanding coal washing facilities in India and therefore CPSI has made some recommendations which could facilitate the establishment of coal washing facilitates in a win-win situation for all stakeholders. These are as follows:
• Most mines should have coal handling plants which will ensure that coal movement within mines is only through conveyor belts and frequent movement of trucks within the mine is eliminated or reduced to a minimum as the maximum pilferage of coal takes place when coal is transported in trucks to railway sidings.
• The coal washing facilities need to be installed as part of the coal handling system. Auto analysers which can give quick and reliable quality checks can be conveniently installed if CHPS having conveyors are used. The entire setup for coal handling including washing should be within the leasehold area of the mine, making no additional requirement for transportation, storage or handling. This will also help counter the perception of coal washing having significant additional costs.
• As per the contract signed by CIL with washery operators the cost of washing is only about Rs 120-150 per tonne, a paltry sum for the benefits gained
• The rejects generated should be practically unusable on account of low carbonaceous content. Such rejects should be put back into the mine fills as per the global standard.
The Ministry of Environment, Forest and Climate Change has recently decided to do away with the need to bring out a notification in this respect. Apparently, this decision has been taken on the views expressed by the Ministry of Power, Ministry of Coal and Niti Aayog. The observations of Ministry of Power alongside my own comments on the same are as follows:
• Washing of coal does not bring the ash content in the coal to zero or negligible.
This is simply not a valid observation as nowhere in the world is coal washed to bring ash down to zero. This is impractical as it involves deep cleaning through chemical additives, and as such, is not preferred or required for use in power plants.
• Washing process results in the production of coal washery rejects which find their way to the market for use in industries and create pollution.
It is true that washing does create rejects but the standard practice worldwide is to bury them in mine fills. If this practice is properly enforced, then the scope for black marketing of these rejects is reduced. Washing should not be blamed for malpractices which are promoted by faulty policies.
• Washing incurs additional cost to the coal besides causing challenges in handling, storage transport and marketing.
This is a persistent perception which can be changed by following the system which CPSI has been trying to promote and has been briefly described above.
• Washing process consumes resources such as land, freshwater and energy. It is also pollution-intensive in terms of air and water pollution alongside soil degradation, requiring advanced mitigation technologies.
A washery should be an integrated part of a coal handling plant in any modern mine and therefore, does not require much additional land. The land that is required is largely for storage purposes. Similarly, water requirements for this process are also minimal given that any washery that obtains environmental clearance has a closed water circuit. With regards to pollution, environment ministries world over are yet to close down a washery for this infraction. The question of soil degradation is also not applicable as standard practice for rejects is to bury them in mine fills. Given all this, the so-called need for ‘advance mitigation technologies’ is pure fiction.
• Due to the increased cost of washing, thermal power plants located along the coast are opting for imported coal.
This observation is not only incorrect but also misleading. First, TPPS (Thermal power plants) near the cost are designed for imported coal, with only a portion of their requirement being met domestically. Second, it is the cost of transportation from distant mines that makes imported coal more viable.
• With the advancement in pollution control technologies, TPPS are equipped to capture almost all pollutants including fly-ash.
The arguments that such technologies make coal washing redundant are misconceived. There are several other advantages which have been ignored while making such a declaration. This clearly indicates that the interest of the power producer and particular NTPC is not in looking at cheap and effective solutions
• Over a period of time, many uses
have been found for fly-ash.
This idea is used as a basis for proclaiming coal washing as unnecessary and can be deemed wholly self-defeating. If fly-ash is of such great demand, then why have a strict law for the use of flyash? It is obvious that the generation of fly-ash is not to be encouraged and if it is produced, it must be used in a regulated manner.
• Unutilised fly-ash can be transported and filled in closed or abandoned mines.
Transporting fly ash to mine fills is certainly a more costly affair compared to putting washery waste (rejects) into mine fills. In fact, in power stations located far from mines, this is an impractical solution.
As mentioned above, the Ministry of Coal also presented its viewpoints on coal washing. The observations of the Ministry of Coal alongside my comments on the same are as follows:
• The quality of coal supplied by CIL
has improved without washing.
This is untrue. There have certainly been some improvements in giving sized coal but most TPPS located at a distance from mines receive coal as big boulders and chunks rather than as sized and washed portions. Ideally, CIL should make arrangements for in-pit crushing which don’t exist. If uncrushed coal is supplied then it damages the crushing and grinding systems at the power stations. More importantly, this wear and tear is largely affected by the quantity of flyash in the coal provided. No power producer is likely to complain, however, as they fear a stoppage of supply from the monopoly holding CIL.
• Based on the present pricing structure of washed coal, improvement in the raw coal quality and size and scope of ash utilisation at the load centre, it is beneficial to use raw instead of washed coal.
The pricing of CIL coal has always been a critical issue as it based on no professional or scientific basis. Being a monopoly it conveniently adopted a cost-plus approach in pricing which impacts quality. Despite having an irrational pricing system which does not adequately take into account quality considerations and energy content of the fuel it is still cheaper for the power plant to use washed coal with higher
GCV and better consistency.
• With the use of supercritical technology in power plants and technological improvement to arrest emissions, unwashed coal can be used more efficiently.
This argument is totally misplaced as the technology deployed in supercritical boilers is based on superheating of steam under pressure and this is more efficiently done when better coal is used. The intention of such technology is not to use unwashed coal but rather increased thermal efficiency.
• Power plants are designed for coal
with a wide variety of ash content.
Use of unwashed coal will not have any effect unless the quality goes beyond the design parameters of the boiler. The original designs of power plants were done in European nations where coal quality was very much superior. In order to use inferior Indian coal, modifications were carried out which pushed up the cost of the plants by 5-7 per cent. It is, however, an indisputable fact that even such modified boilers function with better efficiency when better (washed) coal is used.
• Washing of domestic coal localises pollution around coal mines which otherwise would have been distributed over large areas.
Studies carried out by BSES for their Dhahnu plant show significant saving in per unit generation cost for washed coal. There is also a huge benefit in terms of transport cost, ash disposal and maintenance of the plant
The view that coal washing is localising pollution and that it is more advisable to spread out this pollution is somewhat absurd. Controlling pollution in one area is certainly more sensible than spreading it out.
Niti Aayog had also made some observations supporting the stand taken by the Ministry of Power and the Ministry of Coal. They are largely repetitive. Two very sweeping statements have been made by Niti Aayog are: Washing process increases the cost of power generation and; no clear scientific evidence is available for showing environmental gain due to washing.
In fact, studies carried out by BSES for their Dhahnu plant show significant saving in per unit generation cost for washed coal. There is also a huge benefit in terms of transport cost, ash disposal and maintenance of the plant. As far as the cost of fuel is concerned, it would see a very marginal increase mainly because of an absurd and irrational pricing structure of coal in India. If there was parity with international prices, the situation would have been different.
It is also a fact that when low-grade coal is burnt in the boiler, then excess energy is dissipated in heating ash and as a result plant efficiency is reduced and emissions also increase. To say that washing has no environmental benefits is incorrect.
In conclusion, a decision bereft of scientific prudence and logic will only harm the country. It would have been more appropriate to have a wider consultation with all stakeholders before making such observations in haste.
The writer is the former-secretary for the Ministry of Coal. Views
expressed are strictly personal