THE RECULTIVATION OF THE RBB-BOR CEROVO-CEMENTACIJA 1 OPEN PIT WASTE DUMP

The development of the human society is unbreakably bonded with the development of industrial production. This increases the amount of mineral resources exploitation, thus increasing the area of degraded soil. The consequences of these processes are many and are destructive for the environment, so if nothing was done, the justification of exploitation would be questioned. Looking into the seriousness of the problem, special care is taken to recultivate the degraded soil and rehabilitate its reproductive capabilities. The basic goal of this paper is the proposal of the solution for the establishing of the conditions for long-lasting, viable vegetation covers on the degraded areas of Cerovo-Cementacija 1 open pit waste dump.


Introduction
The quality of the environment at the area of the Cerovo-Cementacija 1 open pit mine, before copper ore extraction and overburden disposal, was preserved and with undisturbed ecosystems.Mining operations degraded the area by both ore extraction and overburden disposal.Structures degrading the soil are the cavity of the pit, waste dumps and industrial facilities such as crushing mill, hydro-transport facilities, eco dams, stock pile etc.
Overburden disposal formed the waste dump which is consisted of two separate dumps, North and South and their areas are given in table 1. [1] Table 1 -total area of degrade surfaces at Cerovo-Cementacija 1waste dump The shape of both waste dumps is mainly elliptic and the average height is about 90 m.The location of the waste dumps and the Cerovo open pit is shown in figure 1.

1
After the end of mining operations the soil can not be returned into its original condition.Ecosystem is irretrievably changed but with modern methods of recultivation it is possible, within relatively short time of 10 to 15 years, to some extent, to give back natural reproductive potential of the environment.

Material and Methods
Mining operations at Cerovo-Cementacija 1 lasted from 1991 to 2002 wit the annual ore output of 2.5 Mt.The overburden was disposed irregularly, with the surface material disposed on the bottom and the material from the deepest benches disposed as the top layer of the waste dump.The waste texture is consisted of sand alumina with alumina content of 35.5 % and sand content of 64.3 % and with pH factor of 3-4.6.This means that the soils cannot cover themselves with protective vegetation without the human intervention.In order to sustain vegetation growth at this area, recultivation must be undertaken trough three main phases [2], preparatory operations, technical and biological phase.
Preparatory operations for recultivation are construction of the access roads, leveling of plain surfaces, humus acquiring, loading and transport to the waste dump.Technical phase of recultivation is consisted of terrace cut-in on the slopes and humus leveling on the finishing planes of the waste dump.
Biological phase gives solutions that associate seeds, plants, soil conditioners, binders, fertilizers in order to integrate the site in its original landscape.

Results and Discussion
Preparatory operations are expensive and complex, but they are necessary.Bulldozer CATERPILLAR D8L with hydraulic tilthdoser, angledoser and ripper will be used for access road construction, leveling of finishing and bench planes and ripping in the depth of 65 cm, the total area to be leveled and ripped is 76 380 m 2 .
Since slope angles of the finishing slopes are steep, about 35, it is necessary to cut small 4 m wide terraces, to make the traffic of light mechanization possible.The terraces will be cut using the articulated multi-functional combined machine FOREDIL model FM500T.This machine meets the demands of efficient cutting and later servicing of the terraces since the height of the terrace slope is 4.5 m and the maximum cutting height of the machine is 5 m. Figure 2 gives the basic dimensions of the terraces.Technical recultivation considers earth and humus digging from the borrow pit, loading and transport to the waste dump and its spreading on the flat surfaces or putting into the dibble holes.Technical recultivation is conducted during the dry period, in July, August, September and October.Earth digging from the borrow dip, loading and transport to the waste dump is necessary because the earth is spread on the flat surfaces for grass seeding and put into dibble holes.
The earth from pit location is of vital issue since it influences on the total costs of the project.The location of Cerovo-Cementacija 2 is chosen because it is at a distance of 800 m.Second reason for this choice is the plan for opening a new open pit mine at that location and because of that the pedological layer will be removed anyway.Table 2 gives the required amounts of earth and humus from the borrow pit.

Table 2 -Required amounts of earth from the borrow pit
Loader ULT-220 will be used for the earth loading and the FAP-2635 and FAP-1314 trucks will be used for the earth transport.FAP-2635 with maximal payload of 16 t will transport the earth to the flat surfaces and the FAP-1314, with maximal payload of 8 t, will transport the earth to the terraces.Average transport distance is 1000 m.Dibble holes will be dug with drilling rig of the combined machine FOREDIL model FM500T.
Biological recultivation considers the choice of plants for forestation of the prepared areas in order to rehabilitate ecosystem.This choice is essential since the soil is poor and hostile to the vegetation due to its bad physical and chemical characteristics.The plants must be fast growing, adaptive, resistant to drought.The first choice is locust tree (Robinia pseudoacacia) and bastard acacia (Amorpha fruticosa) [3,4].
The plants will be planted in autumn, in 1.5 X 1.5 m triangular configuration for the locust tree and 1 X 1 m for the bastard acacia.The amount of necessary dibbles is 5 132 per hectare for locust tree and 11 494 dibbles per hectare of bastard acacia.The number of dibbles should be increased by 10% due to the damage during transport and handling.The dibble holes are square, 50 cm wide and deep. 2 kg of manure and 50 g of fertilizer (NPK 15:15:15) are added to each hole.The number of necessary dibbles is shown in table 3.

Figure 1 .
Figure 1.The position of the Cerovo-Cementacija 1 waste dumps and the open pit 1-Open pit, 2-North waste dump, 3-south waste dump