Abstract

RMU Rembas coal mines, with tradition of over 150 years in coal mining, experienced numerous mine fires, sometimes causing closing of entire mines for long period of time. Mine fires occurred very often, due to brown coal strong disposition to oxidation and self – ignition.
Beside usual measures for preventing mine fires, special attention should be paid to barricading of worked out areas and prevention of air flow in caved areas. Quality and maintenance of barricades are essential in prevention of mine fires in worked out areas.
In October 2006, at Strmosten mine, one of the Rembas mines, due to decreased coal extraction, high degree of carbon – monoxide CO appeared at transport drift TH-4 in OP-1 section. CO is a direct indicator of mine fire and later it was followed by smoke.
To avoid further development of mine fire, temporary barricades (named PIP 10 and PIP 11) were placed at No 35 and No 38 drifts. Concentration of gasses was measured on stationary instruments, along with mobile instruments, which were used to measure concentrations behind barricades. Used mobile instruments were “ORSAT” apparatus and “OLDHAM” instrument.
This paper provides air analyses before and after placement of barricades.

Abstract

Blasting in drifting at underground coal mines has to meet numerous requirements in safety and techno – economic efficiency. Meeting these requirements is possible only in case of choosing optimal parameters for actual conditions of blasting. This paper shows basic principles for determination of blasting parameters in drifting. Limitations in technology and regulations cause difficulties in determination of explosive type, blasthole loading, layout and length of blastholes, initiation schemes.
After the analysis of currently applied blasting technology, this paper suggests changed blasting technology, based on theoretical and practical knowledge and experimental work in four Serbian underground coal mines: Senjski rudnik, Stavalj, Jelovac and Lubnica. Main parameters and gained results of new blasting technology for first two mines are presented. Blasting technology was changed through blastholes layout, load weights, initiation schemes, blasthole length and quality of blasthole sealing. Results have shown improvements in explosive consumption and efficiency of blasting. Besides, percentage of coarse fraction has increased, thus improving overall economic results.

Abstract

In the paper are presented some from us proposed and defined new indices and parameters for technological efficiency estimation, applied to grain size classification operations. In the same time some today in the theory and praxis frequently used indices and parameters are comparatively short reviewed. Also, it is pointed out on the possibilities for use of new defined indices in the classification or separation process quality analysis and for investigations and control of production processes.

Abstract

This paper presents some investigation results about connection between degree of minerals liberation and flotation, responding to flotation plant “Veliki Krivelj”. There are two main degrees of liberation among the sulphide minerals and gangue, and copper minerals and pyrite. Both of two liberation degrees strongly affect on flotation recovery of copper minerals as well as on copper concentrate grade. This paper deals with figures which give some dependence among the degree of liberation, copper recovery and concentrate grade.

Abstract

The main technological indicators of copper flotation which determine the level of revenue per mass unit of processed copper are utilization and the content of copper in concentration.
This study describes the economic-technological model of copper flotation which can help determine, for the given technological and market conditions, an optimal percentage of copper in concentration, whereby the maximum revenue is achieved per ton of the processed ore in the process of flotation.

Abstract

CThe assignment problem belongs to the group of optimization problems. This paper gives an example of using assignment problem solving for a process optimization in mining and mineral processing.

Abstract

Smelter slag, a by-product of metallurgical processes, was made and dumped for over 100 years of ore exploitation in Bor Copper Mine. Smelter slag dumps with approximately 16.500.000 tons of slag and 700-1000 tons of daily produced slag in Bor Copper Mine smelting plant, represents a significant economic potential, as well as big ecological problem.
Researches have shown that it is possible to process smelter slag without residue, using so called “wastefree technology”. This technology represents a complementary technology of several technological processes: flotation and leaching, utilized for recovery of copper from smelter slag, followed by magnetic concentration, where magnetic fraction can be used as suspensoid in heavy media separation processes and non-magnetic fraction that could be applied for infrastructure for roads production, construction or construction material industry.
All this signifies that technological process for processing smelter slag can be verified as technology without residue or wastefree technology.

Abstract

The contribution describes the results of high-gradient magnetic separation of dust outlets from rotary furnaces collected in electrofilter. The separation was performed by the both ways, the dry and wet ones at a magnetic field induction in the range from 0,09 to 0,30 T. As to main components, the dust outlets contain 26–28 % of Fe, 16–18 % of SiO₂ and 1,50–1,65 % of Mn.
Under application of dry way growing induction of field results in an increasing of mass yield into magnetic product from 35 % to 66 %, iron and manganese contents gradually decrease from 35 % to 31 % and from 1,92 % to 1,72 %, respectively. The content of SiO₂ enhances from 11 % to 12 %. The recoveries of main components into magnetic product grow together with increasing of magnetic field induction, namely for iron from 44,75 % to 76,13 %, for manganese from 44,36 % to 75,36 % and for SiO₂ from 22,42 % to 46,54 %.
Similarly, as to wet way of separation, growing induction of magnetic field also results in enhancement of magnetic products mass yields, i.e. from 31,86 % to 37,03 %. Iron and manganese contents in magnetic product decrease from 45,71 % to 44,21 % and from 2,74 % to 2,71 %, respectively. The SiO₂ content increases from 1,20 % to 2,55 %. The recoveries of iron and manganese enhance together with a growing of magnetic field induction from 52,35 % to 59,54 % and from 54,03 % to 61,68 %, respectively, but recovery of SiO₂ only from 2,24 % to 5,26 %.
Thus, under application of dry way of separation the higher recoveries of utility components, namely iron and manganese, into magnetic product can be achieved. On the other hand, wet way of separation enables to attain at lower recoveries of utility components cleaner magnetic product, i.e. higher contents of iron (by 10 %) and manganese and also by 10 % lower content of SiO₂.

Abstract

The production of waste materials, such as tailings, from mining activities can have a significant impact on the environment. Most tailings dams contribute to the pollution of subsurface waters. Assessing the potential effect that the construction of a tailings dam will have on an area’s groundwater system is of great significance. The eventual impact can be evaluated from construction methods of the tailings dam, the tailings chemical and physical composition, hydraulic conductivity of the tailings itself and the groundwater systems that are present in the underlying systems. South African aquifers consist largely of fractured rock (> 90%) which can serve as conduits while rock matrices serve as storage reservoirs for water and pollutants. This paper includes methods to assess the seepage of pollutants into the subsurface aquifers. These include a risk based approach and mathematical modeling to determine the possible impact on groundwater systems.