In the majority of the mine area the upper split of the seam H11B is of exploitable thickness, being 0.60 meters or thicker.
There are coal resources below the -1000 meter level in H8 seam but these can only be exploited after the water level has been pumped down. The H8 seam below the -1000 m level has an average thickness of 1.15 meters. To the west of the faulted area and the abandoned workings, the H8 seam becomes thinner being predominantly less than 0.60 meters thick and is of no current economic interest.
2.3.7 Mine development plan
To the north of the main mine site H11 coal seam outcrops, and access into the seam will be via two inclined drifts which are being driven from a point near to the outcrop. The site of the portals is some 1.5 kilometers to the north of the main mine curtilage and is called the VNP. The first 560 meters of the two drifts is now complete, and access into the first longwall to the east of the drifts (east one longwall) has been developed. To date, more than 2,500 meters of roadway development has been completed.
To produce "early coal", 4,000 tonnes of coal will be mined at VNP on a manual basis for a period of three months from the East 1 block, increasing to 11,000 tonnes per month by applying conventional mining methods and local manufactured equipment.
As the inclined drifts are extended and more working places opened up additional developments can be introduced and retreat longwall production established. Retreat longwall mining is accepted globally as being significantly more productive than advance longwall, and this has also been demonstrated at Verticalnaya in the past. Typically the output from three advance longwalls can be achieved with two retreat longwalls.
The mining sequence plan at VNP has East1 as the first advancing face followed by West1.
East1 will set off with conventional props and bars which will initially constrain the output to around one strip of coal per shift. West1 will also utilize the same equipment and will therefore also be limited to around one strip per shift due to the laborious task of advancing the face supports. The opportunity does exist to significantly increase early production from the mine through the use of mechanized long wall sets, subject to the availability of finance.
The inclination of the coal seam is 18 degrees therefore, all longwall gate roadways will be driven along the strike maintaining the longwall face on full dip.
The thicker section of the seam h11 is irregular in shape with some minor associated faulting. Therefore some of the longwalls planned will operate in both h11B and h11 as they work across particular blocks of Coal reserves.
Therefore the longwall equipment specified will be a ranging drum shearer cutting machine, together with heavy duty hydraulic roof support. The height range of the roof supports being 0.8 to 1.6 meters to accommodate the variable coal seam sections.
H8 coal seam will be accessed and operated via the existing Verticalnaya Mine shafts. The skip shaft will not be used for coal winding but will be equipped for the winding of men and materials down to the lower horizon at 1,250 meters. A cross measure drift will be driven to intersect the H11 seam being developed from VNP before continuing on to the H8 seam. This is to establish a mineral clearance system from both H8 and H11 seams to the surface VNP site.
Using a conveyor belt for coal clearance compared to skip winding provides the following advantages.
-- higher production capacity, not restricted by maximum skip capacities;-- longer periods of operation per day, skip and shaft maintenance requires an average of 4 hours per day;-- Coal from the two seams can be kept separate if required for process and marketing purposes; and-- Provision of a walk-able outlet as a second means of egress.