How Indian steel industry would suffer

The environmentalists in Australia has plotted a very powerful plan, which may affect the export of coal from Australia. All the projects will be delayed and production will be hampered in 2012 and 2013.

The coking coal that is fed to the coke ovens of steel plants in India are mainly exported from Australia. As the coal export will plummet, the steel industry will look towards Indian coal to feed their plants. But the domestic coal is by far insufficient for Indian Steel Industry, as the coking coal in India is very limited. The power sector has maintained the price structure for non-coking coal but for coking coal it will change. Thus, increased price of coking coal and reduced supply may lead to astronomical prices of steel.

The price increase may stop many construction projects in the middle, thus reducing the demand of steel. The share market will plummet. Index of Industrial Production(IIP) which is suffering a lot these days will further suffer and may again go south. The pressure may be felt by captive mines, though there is very little potential there, but increased pressure of production may lead to neglecting safety practices. Reduced safety may lead to accidents, and this may further hamper the production. The coming financial year would be baleful for steel industry.

This may lead to lesser demand of power in future by steel industry and thus power sector may diversify their field of interest. The surplus power may be diverted to domestic purposes which will be a great step towards inclusive development. It may also fuel the research being done in Smart Grids.

Planning a new mine

Planning of a new mine is not as easy as the following 7 steps may seem, but the following is written to give a first hand idea to the reader about opening up a mine:
Exploration Stage
1. Regional Drilling by Geological Survey of India- Prediction of potential blocks on the basis of geological projection and primary exploration in which stage a few boreholes are drilled to test the prediction.
2. Detailed exploration by Central Mine Planning and Design Institute(CMPDI, a coal india ltd subsidiary) or Mineral Exploration Corporation Limited(MECL, under ministry of mine)- Intensive exploration which determines the essetial characterstics of the deposit-structure, continuity, chemical properties and features which could affect mining operation.
Strategy Report
3. Geological Report- On the basis of exploration and a geological and quality evaluation, a geological report is prepared which takes the form of a finalized appraisal of the prospects of coal.
4. Mine Planning- The strategy report also outlines the mining strategy and would point out any special aspects which relate to the possible mining and surface developments.
Feasibility Report
5. Feasibility Report- A feasibility report is prepared after the preliminary appraisal of the deposit has been made. It can be considered as the main phase of planning and designing. It lays down the main policy concerning investment and production. The report contains two main parts:

• Technical: Geology, production, technology, Method of entry, system of exploration, beneficiation, power supply, transport, equipments, employment.
• Economic: Total capital, productivity, production cost, sale price.

6. a. The feasibility report is submitted to Government of India for approval and allocation of fund.
    b. Detailed Project Report (DPR) : DPR is drawn together with drawings, specification sent to concerned colliery for implementation.
    c. In recent times, it has become mandatory to have the projects cleared from environmental angle before mining can start. Accordingly, for each project Environment Management Plan(EMP) is prepared for submission to the Ministry of Environment and Forests to obtain the approval of Department of Environment (DoE) to undertake the mining operation. An EMP contains status of project and mining technology, pre-mining environmental scenario, Environment Impact Analysis(EIA), control and montoring measures, economics and implementation programme.
7. Production to Target.

Bearings

Bearings are the most important part that can be tweaked to get better efficiency from a machine with rotating parts. Three most important types of bearings are discussed here.

1.       Bush Bearing: In mines, pumps are the most common mechanical equipment that can be found and for a multistage turbine pump, bush bearing plays an important part. A bush bearing consists of a cast iron housing which houses a brass or gun metal bush and the rotating shaft, rests inside the bush, which is of plane cylindrical shape. A thin film of oil separates the two surfaces.  A bush bearing is used for small diameter shaft (<75mm) rotating at high speed. The bush is tightly fitted in the block and a set screw is driven partly in the bush to prevent its rotation. Oil lubrication is done through a hole provided in the block extended to bush.

Bush bearing

Plummer Block

2.       Pedestal or Plummer Block: It is a form of bearing where the brass of the bush bearing is separated in two halves which are housed in pedestal body of cast iron.  A cast iron cap is bolted on the pedestal body to cover the top brass. To prevent rotation of the brasses within the block, a lug is provided in each half brasses and it fits in the recess formed in the pedestal body. The face, along which the two brasses rest against each other i.e. the joint, is parallel to its length of the shaft. Coefficient of friction between the shaft and the bearing is of the order 0.01.

Split Bush Bearing

Ball Bearing

3.       Ball and Roller Bearing: These differ from the bush bearing discussed above as the rotating shaft is separated from the stationary portion by means of intermediate balls or rollers which roll freely between the two surfaces. A ball/ roller bearing consists of following parts:

·         An inner race: It is fitted tightly with the shaft and revolves with it.

·         An outer race: It is stationary and is push fitted in the enclosed housing.

·         Row(s) of balls (or rollers) running in the groove formed by the races, the difference in the radius of the two races is 5-10% greater than the radius of the balls) or rollers.

·         Cage/Separator: To separate the balls (or rollers) and maintain them at correct distance apart.

The races and ball are of high carbon chrome steel having hard surfaces. They are machined and ground to within limits of 0.0002am, and highly polished. The cage may be of steel, or brass or a synthetic material.

Grease is used for lubrication and preventing rusting and foreign materials entering into the bearings.

Roller Bearing

The roller bearing can carry twice the load of a corresponding ball bearing, and it is able to move axially within its races to adjust for slight variation in shaft length rather more careful mounting than a ball bearing in order to maintain accurate line of contact. The friction is as low as 0.001 in ball/roller bearings, just a bit higher at the start than when running.

exploded view of a ball bearing

explosibility mixture, methane

Q. How to calculate the lower explosibility mixture (consists of methane and other hydrocarbons) ?

A. Let's put some facts here before solving main problem i.e explosibility mixture. Those are as follows:

(1) Presence of firedamp (mostly methane) in air between 5.4% and 14.8% forms an explosive mixture;

(2) The maximum explosive violence is produced when the explosive mixture contains 9% of firedamp;

(3) If temperature and pressure are increased substantially, a fire damp between 2% and 75% (including both the limit) might also form a explosive substance;

(4) If the percentage of black  damp (CO2 and excess nitrogen) exceeds 35%, the atmosphere becomes non-explosive irrespective of any percentage of fire damp;

(5) Fine dry coal dust lowers the lower limit of explosibility of the methane-air mixture to well below the usual 5%.

Now, we have a tested formula for calculating the lower explosibility mixture(LEM) and that is :

LEM= 100/((G1/g1)+(G2/g2)+(G3/g3)+.....)

Where Gis (i=1,2,3....) are contents, in percent by volume , of each combustible component of the mixture

(That means sum total of Gis must be 100)

and gis (i=1,2,3.....) are lower explosion limit of each component

Let's take a example to apply the above stated formula.  If we have a mine atmosphere data as follows:

CH4  (G1=70%,g1=5%), H2 (G2=15%, g2=4.1%), C2H6(G3=15% , g3=3.2%)

Then LEM =  7.5% approx 

GHV or HHV,LHV or UHV

Q. Define different heat related terms such as GHV or HHV, LHV or UHV.

A. Let's discuss the full form of various acronyms stated above.
     GHV-- gross heat value
     HHV-- higher heating value
     LHV-- lower heating value
     UHV-- ultimate heat value

As far as GHV and HHV are concerned, they are two terms for the same topic.Let's discuss GHV and LHV

(1) GHV or HHV:The higher heating value is experimentally determined in a bomb calorimeter. The combustion of a stoichiometry mixture of fuel and oxidizer in a steel container at 25° is initiated by an ignition device and the reactions allowed to complete. When hydrogen and oxygen react during combustion, water vapor is produced. The vessel and its contents are then cooled to the original 25°C and the higher heating value is determined as the heat released between identical initial and final temperatures.

One point is to be noted here that water is considered as fuel in GHV, contrary to LHV.

(2) LHV or UHV: When the lower heating value (LHV) is determined, cooling is stopped at 150°C and the reaction heat is only partially recovered. The limit of 150°C is an arbitrary choice.



When these terms apply to coal, we consider intrinsic elements of coal--which are capable of producing heat. There are basically three terms responsible for heat-- fixed carbon(C),sulphur(S),hydrogen(H). Apart from those, coal contains water,nitrogen,phosphorus,etc.A high carbon containing coal has approximately same value for UHV and LHV. As carbon contents reduce, UHV value becomes greater than LHV's.

We can calculate UHV or LHV with some constraints as follows:
UHV(Kcals/kg)= 8900 - 138 ( A(ash %)+ M(moisture %) )

Constraints are that if the non coking coal contains less than 2% moisture and less than 19% volatile matter,from the value calculated by the above formula,deduct 150 Kcal/kg for every 1% VM(volatile matter) below 19% and that gives the actual UHV for coal.


A common method of relating HHV to LHV is:

HHV or GCV  = LHV + h_v x (n_H2O,out/n_fuel,in)

where h_v is the heat of vaporization of water, n_H2O,out is the moles of water vaporized and n_fuel,in is the number of moles of fuel combusted.

Blasting Practices at Open Cast Mines

One can easily say that the most important part in extraction from an open cast mine is blasting and by following some simple standard practices, a high degree of productivity can be attained.

Open cast blasting

Following are some important facts related to blasting practices in open cast mines:-

1. Drilling: There are two major types of drilling techniques being used

• Down the Hole (DTH): It is used when the blast hole diameter varies from 100mm to 380mm and the depth of blast hole is 12-15m.
• Rotary: When the blast hole diameter > 400mm and the depth is about 20m, rotary drilling is used.

2. Bench Height: This depends on the excavator employed in the operation i.e.

• Shovel (4.6m3, 6m3, 8m3): 10-12m
• Dragline (24m3/ 96m): 30m

3. Blast Hole Diameter: Up to bench height of 8m, 100mm,, 150mm, 163mm of blast hole diameter is preferred but for bench height > 8m, a minimum of 250mm diameter of blast hole is efficient.

4. Spacing and Burden: In coal measure rocks spacing varies from 3-8m whereas burden is selected about 0.8 times the spacing.

5. Depth of sub-grade drilling: In coal mines the length of sub-grade drilling for a bench height 8m is generally 0.3m.

6. Explosives: In Indian coal mines nitroglycerine based explosives, slurries, Ammonium Nitrate and Fuel Oil Mixture(ANFO) and Liquid oxygen type Explosive(LOX) are the main explosives which are used.

Slurries are mostly used in Open Cast mines because of it is

• water resistant
• has high strength
• has high coupling characterstics
• has good fragmentation

Metalized and Aluminium slurries are used. Also, Site Mixed Slurry(SMS) has been introduced.

ANFO is not generally used because of  its

• low density
• low pressure generation
• poor water resistance

 Limitation of the use of LOX is due to

• limited availability of oxygen making reservoir and soaking plant near mine site
• difficulty in preparation of LOX cartridge
• availability of other cheaper, safer and efficient explosives.

For coal mines special Oxygen based explosive LOXITE-C is used.

 For Iron ore mines:-
1. Bench Height and Hole Diameter: If the bench height is 10-12m, then blast hole diameter should be 150mm, if the bench height <6m then blast hole diameter should be 100mm. In rare cases, 250mm blast holes are selected.

2. Spacing and Burden: In case of 150-165mm blast holes spacing and burden varies from 3-7m whereas height of the bench varies from 8-12m.

3. Stemming Height: It should be 30-40% of the hole depth.

4. Sub-grade drilling: 10-20% of hole depth.

5. Explosives: LOX, Open Cast gelignite, GN-1, slurry explosives, ANFO, metalized and Aluminium slurry, Site Mixed Slurry.

For Limestone mines:-
1. Bench Height: 9-12m

2. Hole Diameter vs Spacing and Burden:

S. No.	Hole Diameter (mm)	Spacing(m)	Burden(m)
1	100	3-5	2.5-4
2	150-160	5-7	4.5-6

3. Sub-grade drilling = 10-20% of hole depth

4. Stemming Height = 20-40% of hole depth

5. Explosive: OCG, ANFO, GN-1, Slurry.

For Coal Mines (Overburden bench), an example
1. height of bench = 13-14m

2. width of bench= 20-25m

3. Avg. Burden= 4m

4. Avg. Spacing= 5m

5. Diameter of blast hole= 250mm

6. No. of blast hole/ blast = 20-35

7. Blasting Pattern is staggered/ rectangular

8. Depth of Blast hole = 13-14m

9. length of face = 40 -100m

10. explosives: Site Mixed Slurry ( VOD = 4500m/s, Relative Weight Strength = 97)

11. Avg. Charge/hole = 200-220kg

12. Charge Length = 4.5m

13. Specific Charge = 0.55 - 0.65 kg/m3 of blasted rock

14. Equipments used: Shovel - 4.6 m3, Dumper - 35T.


In the above articles, there are a few terms that are used without definition. Please ask for any definition that needs explaining by commenting on the article.

Coking and Non-coking coal

Q. What is the basis of grading of two types of coal -- coking, non-coking?

A.---Coking coal is graded on the basis of ash percentage as follows:

Range of ash %(A)	Name of grade
15<A	Steel-I
15<A<18	Steel-II
18<A<21	Washery-I
21<A<24	Washery-II
24<A<28	Washery-III
28<A<35	Washery-IV

 ---Non-coking coal is graded on the basis of UHV(ultimate heat value) as follows:

Grades	UHV range in Kcals/kg(R)
A	R>6200
B	5601<R<6200
C	4941<R<5600
D	4201<R<4940
E	3361<R<4200
F	2401<R<3360
G	1301<R<2400

Article ZERO

"A man would do nothing if he waited until he could do it so well that no one can find what he has done"

This exceedingly inspiring quote by Cardinal Newman is the torchbearer of this initiative. It is just a beginning which will become a success with our combined effort.