Presented by

MD.Saddam HussainB tech mining

*Underground coal gasification

INTRODUCTION: Mining process is commonly done in two ways

opencast mining and underground mining.

As the population increasing their artificial needs are also increasing and by these two methods we are unable to reach the needs of increasing population.

Now a days modern methods are implementing in mining and one of them is UNDERGROUND COAL GASIFICATION Process.

Underground coal gasification (UCG) is an industrial process which converts coal into product gas.

It is an in-situ gasification process carried out in non-mined coal seams, using injection of oxidants to burn the coal and bringing the product gas to surface through production wells drilled from the surface to coal seam.

The product gas could be used as a chemical feed stock or as fuel for power generation.

The technique can be applied to resources that are otherwise unprofitable or technically complicated to extract by traditional mining methods and it also offers an alternative to conventional coal mining methods for some resources.

*ProcessUnderground coal gasification converts coal to gas. Gas produced is known as synthetic gas(syngas) or product gas.Gas is produced and exhausted through wells drilled into the non-mined coal seam, The drilled holes are named as Injection well & Production well.

Through injection well oxidants (air, oxygen or steam) are supplied to ignite and fuel the underground combustion process.

Production well is used to bring product gas or syngas to the surface.

The calorific value is nearly 800 – 1200 K Cal/NM3 and it may reach up to 1500 K Cal/NM3 also.

Syngas uses

This process decomposes coal and generates CO2, CO, H2, N2, and CH4. In addition to them, there are small quantities of various contaminants including Sulphur oxides (SOX), mono-nitrogen oxides (NOX) and hydrogen supplied (H2S). As the coal face burns and the immediate area is depleted, the oxidants injected are controlled by an operator. Which helps us to control the flow rate and burning capacity of the coal.

There is no surface impact after completion of UCG process

NEED OF GASIFICATION TECHNOLOGY

Fuel-wise Primary Energy consumption in %.

Coal production has been increasing over the past 10 years, despite calls for lower emissions and continued research into the development of alternative energy sources. The International Energy Association (IEA) predicts an increase in coal usage of 55% to 2030 as emerging nations develop industrial infrastructure and the world moves from reliance on depleting supplies of oil and gas.

FUEL INDIA WORLDOil 32 37Natural gas 8 24Coal 54 27Nuclear energy 1 6Hydro electricity

5 6

Total 100 100

Coal will increasingly be used but UCG offers, a cleaner, cheaper and safer method. However nearly 85% of known coal reserves are deemed un-mineable with surface mining techniques, being too deep, too remote, and too economical or of poor quality. The majority of countries with large coal reserves have few alternative indigenous energy sources. many of the poorest nations have low rank coals that emit noxious chemicals and low energy when conventionally mined.

It is in these regions that UCG has much to offer, so many are now turning to UCG to fully utilize this valuable resource, which many experts believe could treble the availability of coal suitable for UCG globally.

UCG is especially suitable for low rank coals like lignite and sub-bituminous coal and bituminous coal.

The calorific value of bituminous coal is 10,500 to 15,000 Btu per pound as mined.

The calorific value of sub bituminous coal is 8,500 to 13,000 Btu per pound, as mined.

The calorific value of lignite coal is 4,000 to 8,300 Btu per pound.

which produces less heat and more CO2 when burned. In addition, the UCG process is an effective generator of large quantities of CO2,hydrogen, now in demand as feedstock for the chemical industry and as an alternative fuel for vehicles

In India most of the mines are closed being coal seams present but the seam is too deep and it cannot be mined because of some economic reasons (such as it does not produces sufficient profits and in other way it causes much losses).

In India an underground mine depth is not more than 400 to 500mts but we are having coal seams present below 600mts.

These seams cant be mined due to heavy depths and some reasons but in such cases we can use the UNDER GROUND COAL GASIFICATION and we can take the complete coal out in the form of syngas and we can produce electricity and etc. Without depending on any others.

This process is so easy and can be done in depths.

ADVANTAGES AND ENVIRONMENTL BENEFITS:UCG does not cause any type of environmental impacts which are usually caused by traditional mining methods.

UCG causes much less pollution do not release gases (SOX, NOX and NOXIOUS GASES) directly into atmosphere.

Coal gasification offers certain environmental benefits compared to traditional coal fired power units, plants using coal gasification technology produce much lower carbon emissions and solid waste, rather the waste products can be valuable for instants, pure sulfur can be extracted from sulphur dioxide scrubbers.

Methane gas produced during this process can be used as a substitute for natural gas.

Another example is the chemical synthetic gas which consists of carbon monoxide and hydrogen. It is the raw material for producing industrial chemical such as ammonia and methyl alcohol.

Compared to the above gasification UCG is much cheaper. Does not disturb land by mining, leaves ash in its natural location and allows on operating. UCG plant to increase its syngas production at minimum capital cost.UCG seems to be most suitable technology to be used in conjunction.

With CO2 storage, providing a reduction of greenhouse emissions compared to surface exploitations.

The gases released during this process can be processed and used in chemical industries, fertilizer companies.

ECONOMICALBENEFITS: UCG is a cheaper process when compared to other coal mining

methods

UCG does not allow gasifier purchase.

Coal transport or purchase is not done in UCG.

In UCG power generation costs is very low.

The gases produced during UCG can be sold to chemical factories.

DISADVANTAGES:The main disadvantage of the underground coal gasification is ground water contamination. Due to the ground water present at the processing area the pollutants released are mixed with in the water and makes it contaminated and poisonous.

SUGGESTIONS TO OVER COME DISADVANTAGE: Contamination can be prevented by proper siting-UCG plants at the

place where there is no groundwater to be contaminated.

Isolating the site from current or future ground water sources and understanding how UCG affects the local hydrology.

Regular monitoring of the groundwater around the UCG operation to take appropriate measures.

Heating and subsidence from UCG might lead to fractures leading to change in ground water flow. Heated water having low density and low viscosity may affect ground water flow.

Where the UCG process has made the surrounding ground water is permanently declared as unsuitable for irrigation or animal feeding.

World wide view of countries using UNDERGROUND COAL GASIFICATION Process

CONCLUSION: Coal is the prime energy resources in India.

Major problems associated with the current coal based technologies are lower efficiency, environment and consequent damages there off.

Coal gasification has been internationally accepted as one of the most viable and effective clean coal technology for various applications with limitations

“I believe that one day hydrogen and oxygen, which together form water, will be used either alone are together as an inexhaustible source

of heat and light” -Jules Verne,

the mysterious island 1874.

*Underground coal

gasification video