Coking Coal Availability for Indian Steel Industry – Issues and Challenges.

Steel demand projections

India has become the 3rd largest steel producer in the world with a production of 91 MT and a capacity of 125 MT in FY 2015-16. The low per capita steel consumption of being low at 61 Kg in India compared to world average of 208 Kg, there is significant potential for growth. As per the National Steel Policy, 2017, the crude steel demand will grow threefold in next 15 years to reach a demand of 255 MT by 2030-31. It is anticipated that a crude steel capacity of 300 MTPA will be required by 2030- 31, based on the demand projections. Even with this demand of crude steel by 2030-31, India’s per capita finished steel consumption would reach only to 158 Kg.  However, achieving crude steel capacity up to 300 MT will require extensive mobilization of natural resources, finances, manpower and infrastructure including land.

Requirement of coking coal

As per the aforesaid Policy, the demand for coking coal is expected to be 161 MTPA; that of non-coking coal for PCI about 31 MTPA and the non-coking coal requirement for DRI route is estimated at 105 MTPA by the FY 2030-31.

The current dependence on imported coal is about 85%, which as per the National Steel Policy is supposed to be brought down to 65% by 2030-31. This indicates that 35% of the total requirement of 161 MTPA by 2030-31, i.e., 56.35 MTPA needs to be met from the domestic sources by the year 2030-31. This is a great challenge for both the Steel Producers and the Coal Producers in the country.

The National Steel Policy aims at increasing the availability of coking coal through overseas asset acquisition, establishing  sufficient number of modern coking coal Washeries, facilitating allocation of indigenous coking coal reserves in the country exclusively to steel sector with no diversion of such coal to any other sector, facilitating exploration and optimal utilization of deep seated coking coal reserves,  expeditious implementation of Jharia Action Plan to improve the domestic availability of coking coal and  taking suitable fiscal measures to support the rising requirement in the steel sector.

Coking Coal Availability in India

Though, India is fortunate to have 3^rd largest share of coal resource in the world, the quantity of coking coal is very limited. Further, due to the “Drift Theory” origin of coal in India, where the woody material was transported to longer distances, carrying along external impurities, made such coals contain very high amount of inert material or mineral matter, commonly known as ash content. These mineral matters are finely disseminated within the coal matrix, which have made the coal more difficult to be washed or beneficiated for reducing the ash content.

Coking coals in India are categorised in three categories, namely Prime Coking Coal, that can form coke for metallurgical purposes without blending with other coals: Medium Coking Coals, that require blending with Prime coking coals for coke making: and Semi-coking Coals that are weak in coking properties but can be blended in small proportions with Prime coking coals for coke making.

Prime coking coals are available in India only in the upper seams (Seams IX and above) of the Jharia Coalfield, which have mostly been exploited in the past and the remnant resources are now available in the surface constrained areas like, Surface Fires, Rivers, Townships, Human Settlements and Road & Rail infrastructures.

Medium coking coals are available in various coalfields in Jharkhand (lower seams of Jharia coalfield, Raniganj, East Bokaro, West Bokaro, Ramgarh, North Karanpura & South Karanpura), West Bengal (Raniganj coalfiled) and, Madhya Pradesh (Pench Kanhan & Sohagpur), which have substantial resources with high ash content.

Semi-coking coals are available in very limited areas of West Bengal (Raniganj coalfield), Jharkhand (Ramgarh coalfield and Chhattisgarh (Sonhat coalfield).

As per the GSI estimates of 2017, the total coking coal resource in India is 34.533 billion tonnes (Bt) with Prime, medium and Semi-coking being 5.313Bt, 27.512Bt and 1.707Bt respectively. Based on the status of exploration the break-up of these resources is as follows¹:

Coal Type	Measured Resource (billion tonnes)	Indicated Resource (billion tonnes)	Inferred Resource (billion tonnes)	Total Resource (billion tonnes)
Prime Coking	4.614	0.698	0.000	5.313
Medium Coking	13.500	12.132	1.879	27.513
Semi-coking	0.519	0.995	0.193	1.707
Total Coking	18.634	13.826	2.072	34.533

1.     Source GSI publication

General characteristics of coking coal

Coking coals are such coals that can form quality coke during carbonisation. Coke quality in terms of cold and hot strength plays an important role in the smooth running of Blast Furnaces. The four most important characteristics of coke that dictate the right quality parameters of coking coals required to make such coke are, Micom-10, Micom-40, CSR and CRI values. These are basically the strength parameters of the coke at different conditions.

Amongst all ranks of coal, depending on their age (Peat, Lignite, Bituminous and Anthracite), only a few bituminous coals possess the required properties for production of right quality coke for the use in a Blast Furnace. As such, the quality parameters of the coking coals are very important for deciding the blend ratio of different coking coals from different sources for making a good coke. The required characteristics of coke are achieved by making coke after blending coking coals from different sources to satisfy the pre-defined proximate characteristics, ultimate analysis characteristics rheological properties, petrographic properties and the ash chemistry.

Important parameters of the proximate analysis are the moisture content, volatile matter and the ash (inorganic residue), each expressed as percentage of total. The ultimate analysis results show the percentages of different elements like C, H, N, S and P.

In the rheological properties, Free Swelling Index (FSI) or Crucible Swelling Number (CSN), Maximum Fluidity (ddpm) and Plastic Range are very important to decide the suitability of any coal for coke making. For high strength coke, various coals used in the blend should have a broad range of common plastic temperature; otherwise coals will not be compatible.

During the process of formation of coal, that is, conversion of wood or plant material to bituminous coal stage, different types of macerals, like Vitrinite, Semi-Vitrinite, Liptinite, Exinite and Inertinite are formed that behave differently upon heating. Only the first four macerals are characterised as reactives. Petrographic properties are determined through microscopic studies of coal samples for determination of their type, rank and mineral matter. General characteristics of coking coals show that the reflectance of Vitrinite (Ro) varies from 0.6% to 1.8%, however, the acceptable range of reflectance (Ro) for good coke making varies from 1.1% to 1.4%. Mean maximum reflectance (MMR), which is denoted as Rmax or MMR is normally 1.066 times Ro value.

The ash chemistry of coal in terms of its composition as CaO, SiO₂, Al₂O₃, Na₂O, K₂O etc. are also important to decide whether the slag of the Blast Furnace will have acidic nature or basic nature.

Thus, it can be seen from the above that selecting a particular coal for coke making requires rigorous testing of the same in terms of the different required properties and making coke after blending the same with other suitable coals to meet the required coke parameters.

Quality Comparison of Indian Coking Coals with Australian coking coal

Australia is the major supplier of coking coal to India and also to the world trade. Indian Steel producers meet their requirement of coking coal largely from Australia and partly from USA, New Zealand, Mozambique, Russia and China. Quality-wise Australian coals are superior and as such are more favoured by the Indian Steel industry. However, the international price of coking coal is very volatile and becomes unaffordable for the steel producers at times.

A comparison of some typical imported Australian coking coal with typical Indian coking coals is shown below²:

Sl. No.	Coal/coke parameters	Australian coking coal	Indian washed coking coal	Remarks
A	Proximate Analysis
	Moisture (%)	1 - 2	2 – 2.5
	Ash (%)	7.5 - 9.8	15.24 – 18.03	Higher in Indian coals.
	Volatile Matter (%)	19.3 - 24.3	18.58 – 24.84
B.	Ultimate Analysis
	Carbon (%)	88.3 - 90	70.9 – 75.1
	Hydrogen (%)	4.67 -  5.0	4.03 – 4.23
	Nitrogen (%)	1.8 - 2.06	1.08 – 1.57
	Sulphur (%)	0.55 -  0.7	0.57 – 0.83
	Phosphorous (%)	0.007 - 0.07	0.026 – 0.18
C.	Petrographic Analysis
	Vitrinite (%)	55 - 70	46.5 – 55.0	Lower in Indian coals.
	Liptinite (%)	0 - 1	0 – 4.4
	Exinite (%)	0	0
	Inertinite (%)	27 – 42	38.1 – 45.6	Higher in Indian coal.
	Mineral Matter (%)	2 – 4	5.9 – 9.9	Higher in Indian coal
	Vitrinite Reflectance (Rmax)	1.17 – 1.55	0.98 – 1.3	Lower in Indian coal.
D.	Ash Analysis
	SiO2	50.3 – 66.5	8.22 – 11.25
	Al2O3	28 – 33.1	4.92 – 5.29
	Fe2O3	2.4 – 7.6	0.01 – 1.05
	CaO	0.2 – 3.9	0.095 – 0.63
	Na2O	0.3 – 0.9	0.001 – 0.052
	K2O	0.85 – 1.5	0.2 – 0.33
E.	Caking Property
	CSN	7.5 – 9.0	5 – 6	Lower swelling index due to higher ash in Indian coal.
	Gray King Coke Type	G5 – G10	C – E/F	Relatively inferior coke type
F.	Giesler Plastometer Value
	Maximum Fluidity (ddpm)	75 – 1100	772 - 2400	Superior fluidity in Indian coal.
G.	Coke Properties
	Micum M40	80 – 84	NA
	Micum M10	7 – 8	NA
	Coke reactivity index (CRI)	21 – 35	NA
	Coke Strength after reaction (CSR)	65 – 72	NA

2.     Source: Compiled from various available sources.

Coking coal price concern

Historically, price of imported coking coal had a downward trend since 2012 (US$ 252.1) till 2015 (US$ 90). From the second half of 2016, there has been steep rises in the prices, sometimes touching the figure of US$ 260 per tonne. Coking coal prices in the international market continue to trend higher since December 2017 on the back of supply tightness in Queensland, Australia. Difficulties in securing loading slots in Queensland for contract cargoes continued to tighten global supply of coking coal in late 2017. In March 2018 the prices are in the range of US$ 220-225 per tonne.

Soaring price of internally traded coking coal is a cause of great concern for the Indian steel producers due to their competitiveness in the world market for the steel products.

Need for demand side management

With the limited availability of domestic coking coal for the required quality and its spiralling high prices in the international market, it is necessary to look at the demand management side. It is more so important when we look at the current consumption rate of coke in Indian Steel Plants vis-à-vis global best practices. The National Steel Policy endeavours to pursue with the Integrated Steel Plants to reduce their coking coal consumption at par with global best practices by resorting to auxiliary fuel injection technologies like Pulverized Coal Injections (PCI)/ Coal Dust Injection (CDI) or natural gas/ syngas injection along with PCI/ CDI.

Targets for the techno-economic performance, as set forth in the National Steel Policy are as shown below:

Parameters	Units	International Best Practice	Current	Target for 2030-31
Coke Rate	Kg/thm	275 - 350	400 - 600	300 – 350
CDI Rate	Kg/thm	200 – 225	50 – 200	180 - 200
BF Productivity	tonnes/m3 /day	2.5 – 3.5	1.3 – 2.2	2.5 – 3.0
Specific Energy Consumption	Gcal/tcs	4.5 – 5.0	6.2 – 6.7	5.0 – 5.5

Coking coal production plan of Coal India Ltd for FY 2019-20

CIL has planned to enhance its coal production to the tune of 908MT by 2019-20. A breakup of the planned production vis-a-vis individual subsidiary is as follows³:-

Subsidiary Name	Total (MTPA)	Coking coal (MTPA)	Non-Coking Coal (MTPA)
			G-10 & superior	G-11 & inferior
ECL	62.0	0.25	44.75	17.0
BCCL	53.0	45.78	7.22	-
CCL	133.5	24.4	45.57	63.5
NCL	110.0	-	96.00	14.0
WCL	60.0	0.52	59.48	-
SECL	239.6	0.14	20.42	219.0
MCL	250.0	-	1.5	248.5
Total	908.10	71.12	274.94	562.04

3.     Source: Published paper in the 5^th International Conference on Coal Washing.

As can be seen from the above, around 71 MT of coking coal is planned to be produced, but due to non-availability of adequate washing capacity in CIL, most of these are being supplied to the power plants. This is the current practice and is likely to continue until the washery construction programme of CIL gains ground.

Coking coal washing - Present capacity and future plans

Most of the coking coals, being produced currently and also projected to be produced in future, are of inferior grade with ash content generally exceeding 35%. The current washing capacity of Coal India for coking coals is around 23.3 MTPA and it has a plan to set up new coking coal washeries to meet the requirement of coking coal for the steel producers. However, as Indian Coking coals have very poor washability characteristics these washeries are planned to wash at 18-19% ash content.

At present the total installed capacity of the coking coal washeries in India is about 31 MTPA which operate at around 20-30% capacity utilisation. Such low capacity utilisation is owing to the fact that most of them were set up 4 to 5 decades ago and not much required improvements were made in them with the changing quality of feed over the years. These washeries were planned with feed from superior grade coals, which have since exhausted.

CIL has identified to set up 18 new coking coal washeries with total throughput capacity of 48.2 MTPA (Source: Corporate presentation of CIL, April 2017) in its various subsidiaries under BOM/BOO concept. Three of these washeries at BCCL with a combined capacity 11.6 MTPA are likely to be commissioned shortly. Other three coking coal washeries with total capacity of 7.0 MTPA are in different stages of construction and are likely to commission by the year 2019-20. Additional one new coking coal washery with throughput capacity of 3.5 MTPA is planned to be set up at Tasra project of SAIL.

In view of the above the total installed capacity of the new washeries and the existing washeries of Tata Steel would be about 59.4 MTPA, which at an average yield of about 45% - 50% can provide clean coals at 18% ash to the extent of 27 to 30 MTPA. As most of the existing washeries would be replaced with the new ones, there still remains much gap between the estimated demand of coking coal from indigenous sources  and its likely availability. Further, it is also important to examine whether, all the domestic coal with 18-19% ash can be blended with imported coal at the steel plants from the point of view of Blast Furnace productivity and the related costs.

Prospect of washing Indian Coking coal at lower ash level

A Committee was constituted by the Ministry of Coal, Government of India in March 2017 under the Chairmanship of CMD, CMPDI with members from Steel and coking coal producing companies, CIMFR and IIT(ISM), Dhanbad for assessing the technical feasibility of washing coking coals (W-IV/ LVMC) to 13% ash content and the cost economics thereof.

Comprehensive studies were made by collecting samples of coking coal from the mines/seam currently under production, conducting washability tests and evaluating the cost of clean coal at 18% ash, 15% ash and 13% ash. The Committee’s major findings were as follows:

1. In general, the desired selling price of clean coal produced on washing W-IV coal is less than the desired selling price of clean coal produced on washing ungraded coal.
2. In the case of washing coal to obtain cleans coal at 13% ash, there is huge generation of middlings as compared to that at 18% ash clean coal. Marketability of such huge quantity of middlings needs to be looked into.
3. In the case of clean coal at 13% ash, it is obvious that significant quantity of coal having coking properties is reporting to the middlings which could otherwise be used for metallurgical purpose.
4. Depending on the quality of raw coal feed (W-IV & ungraded) and its washability characteristics, the theoretical yield of clean coal at 13% ash varies from 13% to 28% and the corresponding middlings at 34% ash varies from 62% to 51%, which is more than double the quantity of middlings generated at 18% ash clean coal. This indicates that huge quantity of coal having metallurgical properties migrates to middlings which can otherwise be used for metallurgical purpose if washed to obtain clean coal at 18% ash level.
5. For washing W-II/ W-III grade coking coal at 13% ash clean coal, new washeries may be set up in the areas where there is potential of better yield leading to favourable techno-economics and the consumer is willing to accept clean coal at that price on long-term basis.
6.  The technology for Washing may be selected on the basis of percentage of Near Gravity Material (NGM) at the cut-off ash, which could be Jig for <20% NGM and Heavy Media for >20% NGM.
7. Washing of coking coal to produce clean coal at 13%, 15% and 18% may be considered based on the overall economics of the project which is greatly dependent on yield%. To have a balance between cost of production, yield and ash%, project specific study needs to be carried out in a holistic manner.
8. In view of the above, it was recommended that washing of coking coal (WIV & LVMC) at 18% ash level will give viable techno-economics for both Steel Sector and CIL.

Emerging Technologies for extracting less than 10%-12% ash coal from high ash Indian coking coals.

A.         Studies done by CIMFR

CIMFR had conducted some studies on grinding of Low Volatile Coking coal to 100 micron size and then beneficiating it by floatation. To achieve the low ash (below 12% ash content, two-stage floatation studies were carried out. The typical results of the rougher and cleaning stage floatation by floatation column is shown in the flow sheet.

This coal has potential to give the product around 10%-12% ash content with 41%-42% yield and second product can be produced around 34%-35% ash having 16%-17% yield. The overall yield in two stage processes is around 57%-58%. The rejected tailings are having 68% ash content.  The second product can be used directly for power generation. There is also the possibility by blending the tailings with product II to use in fluidized bed power generation plant to utilize the full combustible values. 

This study indicates that there is ample potential to get up to 10% ash coking coal from Indian ROM coking coals. However, its cost economics and the technology for binding the 100 micron size product, to make them transportable, needs to be developed.

It is suggested that Indian Steel Producers should commission Research Organisations to develop this technology to recover maximum carbon from the domestic coking coal. It may be worth mentioning that the technology for drying and conditioning micron size coals to form a product in pellet size has already been developed in USA, which would require to be adopted in this technology. 

B          Recent developments in coal refining (reducing ash in clean coal to around 5%)

A remarkable new coal technology has been developed recently in the USA where coal refuse from the coal washeries are processed to efficiently separate it into hydrocarbon, mineral matter and water factions. The process takes place at a very small particle size (averaging around 100 microns) enabling the particles to respond to nano agents – the coal becomes very hydrophobic, facilitating very effective ash-mineral separation. The hydrocarbon fuel separated from this process is an extremely high quality coal and is produced as a robust, stable pellet with approximately 2 % moisture and 5% ash. As a fuel, such low ash-low moisture hydrocarbon fuel delivers substantial value in use for power stations (for thermal coal) and steel production (for coking coal).

Pilot scale demonstration of such separation at a capacity of 3 tph module has been made with the result of substantial reduction in the ash content and improvement in the FSI of coking coal rejects. It is also gathered that a number of small modules of 3 tph could be clubbed together to create an integrated capacity of 2 MTPA throughput for such processes.

Though, the above mentioned development is quite new and requires to be evaluated on commercial scale, the development itself appears to be innovative and requires a closer scrutiny for its use on a commercial scale for treating Indian coking coals which have inherently high ash content.

Conclusions

Indian Steel Producers are facing a lot of challenges in meeting the competitiveness of marketing steel in the world market due to highly volatile prices of coking coal. This is further compounded by the mammoth plan of increasing steel production in India in the coming 15 years. Domestic coking coal, having high ash content and difficult to wash characteristics, restrict their washability at lower ash levels and become extremely costly compared to the internally traded coking coals. However, in order to control overall costs of production of steel, it is necessary to blend domestic coking coals to the maximum extent, without compromising on the overall cost of production of steel. A lot of R&D work has to be undertaken to harness maximum quantity of coal at lower ash from the domestic coal. The conventional system of gravity based coal washing is not a solution to the increasing demand of coking coal. The emerging technologies need to be developed as discussed in the previous paragraph need to be tried and established to make them commercially viable to increase the availability of domestic coking coal for metallurgical purposes. The best way to maximise utilisation of Indian coking coal would be to conventionally wash it at 18% ash and treat the rest of coal (middlings and rejects) in the new technologies to reduce the ash to below 8-10% and blend it with 18% ash clean coal to reduce the overall ash content of the blend.