workings, expected technological losses of ore,
technological dilution, cost of extracted ore
mass).
• criteria for selecting variants of mining systems
(mining depth, ore body thickness and dip,
physical and mechanical properties of ore and
country rocks);
From these passports, based on comparison of the
criteria for mining systems selection and actual
conditions at mining sites of the deposit, variants of
systems for specific blocks are selected. It should be
noted that in practice these conditions are unique and
are not repeated at other mining sites.
On the basis of the selected mining systems,
mining blocks are designed.
However, designing implies certain complexity
consisting in the fact that the right choice of the
mining system does not guarantee its highest
economic results. This situation is due to the fact that
in typical passports there are only fundamental
solutions for block designs and the technology of
stoping treatment for certain simplified forms of ore
bodies, elements of their occurrence. Yet, in practice,
real characteristics of ore bodies have significant
deviations from average values, and this leads to
specific economic results of mining which will
naturally differ from the values indicated in the
passports of the systems. Therefore, in order to obtain
the highest economic efficiency of stoping, the
selected variant of the mining system still needs to be
parametrically adapted to conditions of a particular
block, and there may be several competitive variants
of systems.
At the mining enterprise, there can be from 4 to
20 mining blocks at the same time and it is necessary
to design more and more new blocks as already
exhausted blocks are decommissioned. Designing of
the kind is a constant and continuous process. These
projects are prepared according to a special
instruction, in which unfortunately there is no method
of detailed economic analysis of decisions made
during designing (
Barry, 2006).
Parametrical adaptation of mining systems is
performed through selecting geometrical parameters
of structural elements of the block without violating
the principle design of the system chosen for it. In
addition, when adapting, the parameters of the
stoping technology are calculated, the general scheme
of which is regulated by the passport. Naturally, the
obtained technical and economic results of ore
extraction and its profitability depend on the level of
constructive, technological and parametrical
adaptability of the entire production and
technological complex of a mining unit to specific
geological and mining conditions of its design and
mining of its reserve.
Such adaptation represents a complex, time-
consuming and responsible process in which many
options of different solutions are considered. Its
implementation requires highly qualified designers
with practical experience in technological design and
mining economics. At the same time, each of their
solutions should be not only due to mining factors,
but also economically justified and optimized
according to the criteria for obtaining the highest
economic efficiency. That is why it is necessary to
have an economic and mathematical model of an
appropriate nature and a system of estimated
economic indicators.
The authors have developed a relevant model and
system of indicators. This model is developed on the
basis of formalization of three important
characteristics of the subject of labour: the Value
represented by the ore reserve; the Value of the ore
reserve; the Degree of the value use when mining.
For this purpose, business structures acquire the right
to mine the reserve. This approach to evaluate the
efficiency of stoping is applied for the first time.
Specificity of application of the above
characteristics consists in the following. The purpose
of stoping is to obtain the industrial reserve of ore
from the monolithic ore massif, the required volume
of ore mass which, in its physical condition (crushed
material with a given granulometric composition),
quality (metal content) and economic characteristics
(cost), allows economically efficient processing it
into commercial iron ore products that meet the
requirements of the consumer (a metallurgical
enterprise). At the same time, the closer to these
requirements the characteristics of the mined ore
mass are, the more cost-effectively ore mass is
processed. Up to 40% of ore mined at mining
enterprises, even without detailed optimization of
mining immediately after extraction, meets these
requirements. But that is not sufficient. To achieve
the highest degree of such conformity, it is necessary
to choose the most optimal technological, technical
and parametrical solutions for implementing each
technological process, which make up the structure of
stoping. However, this is currently not performed,
and designers are guided only by common solutions
without their detailed economic analysis.
2.1 The Structure of Stoping
As mentioned above, stoping involves a number of
technological processes that are strictly sequenced
and rigidly related. This sequence is given in Fig. 1.