K. K. Kaysenov, A. A. Kurmankozhaeva GB 5
Almaty, Kazakhstan
EFFICIENCY
OF THE RATIONAL USAGE
OF
THE OFF BALANCE AND LOST
ORES
ON
THE DEPOSITS OF KAZAKHSTAN
In the
visible future on the all deposits of the non-ferrous metallurgy of the country
the technological situation will become more complex due to decreasing balance
reserves
of the ore and continuously increasing
the depth of the mining level. At the same time the mining production
will inevitably face up with the increase of the effect of the rock pressure on
general excavations, first workings and stopping excavations what
will
lead to increasing losses of the balance reserves in the ore blocks
left for their saving and maintenance. The most important factor accelerating a
premature closing of deposits is uncontrolled natural phenomenon – decrease of the
content of the minerals in the ore and growth of the reserves losses from depth
mining.
At present time it
is possible to state with more probability that at the latest than 15-20 years
due to complete extraction of the ore reserves balance, the
deposits of Zhezkazagan, Maleevsky, Tishinsky and other deposits
of non-ferrous metal will be closed, as for instance - Achisaysky and Mirgalimsky deposits some time
ago famous all over the world. In that case
hundred thousands of workers and all population employees
in
different areas of the infrastructure of industrial cities inevitably will lose
employment what will lead to
an
acute social tension and poverty of more than 400 thousands of population.
However a prevention from such a situation can be found by
developing and implementing progressive technologies and machinery allowing to
efficiently use the off balance poor and lost rich ores. New research work is
seeking how to provide a longer period of exploiting active deposits
with large reserves of the off balance and lost ores. Only in the
Zhezkazgan copper massive they consist of more than one milliard of tons plus
enormous quantities of rich ores left in the exploitation process as lost ores representing
a
volume of up to 40 % from the whole balance reserves of the mine field.
Therefore the prevention of industrial
cities before an inevitable death is a very
serious and important problem for the whole state both in industrial and social
areas.
At present time
technologies
of copper production directly on the places of the mining of ores and
technology of drilling and blasting works are being elaborated. Technology of
the copper production directly on places of the off balance ores
exploitation, new boring machinery and technology for blasting wells and
bore-holes with the use of concentrated charges of explosive and wave curtain
as their stemming are being developed for improving exploitation
conditions in the deposits. New boring shell for boring wells of alternating section and parabolic wave reflector
as well as technology of the subterranean block lixiviation are being
elaborated. Elaboration of the copper production directly on places where the off balance
ores exploitation takes place with the help of new technical
means applying boring shell of wells of alternating section and wave curtain represent
an effective
approach which is being implemented into the exploitation
practice. By implementing the new means the production costs
decrease by 30% in comparison with traditional
methods. Processing of the off balance ores by the method of
subterranean block lixiviation is performed three times cheaper than by the
traditional
processing method. Therefore with equal production
costs volumes of the exploited off balance ores might be increased
because their processing
is many
times cheaper than the processing of
the balance ores.
Under such conditions the period of the
efficient
exploitability of Zhezkazgan deposits might be prolonged for many
years.
The
main
advantage of this project is to prolong the
life of
many deposits and by this way to provide social wealth to
industrial cities. Elaborated technologies of the boring explosion works,
production of non-ferrous and precious metals directly on places of ores exploitation might be
implemented in all the ore deposits of the Republic of
Kazakhstan.
The project deals
with realizing a complex of problems. There is a task to change the traditional drilling and blasting
technology and to develop completely new technology of well-boring
allocating in them
concentrated explosives for the even small crushing of the exploited ore. In the
opposite case the creation of the processing technology with
the use
of hydrometallurgical methods will face difficulties. In the group explosion
of the fan wells the quantity of explosives allocated in them
along their length should be increased proportionally in accordance with the continual
uninterrupted
increase of the distance between fan wells along their length. This might be
achieved if all fan wells will be bored with a
continually
increasing
diameter along their length. But such a way of boring wells
is practically impossible. For realizing
the
mentioned task the only way remains consisting in well-boring on the
certain lots to create in them holes with the increased diameter in the way of
spherical open pits for the allocation of required quantities of explosive
substances, i.e. fan drilling should be performed with the alternating section.
Use of the blast holes of the alternating section will allow to
significantly
decrease the volume of the boring works and to
provide
even crushing while dislodging the ore; that will considerably decrease net cost for
exploiting one ton of the ore. There are backlogs that envisage to reject of the
traditional technology of the explosion of the wells and bore-holes, pit mouths
of which are closed with the stemming (plugs) made from the wet clay and
sand. In this method explosive energy is lost by 30%. Envisaged technology
substituting the old one by a new one with the
wave curtains (made from plastic and strengthening the blast waves of
the explosion in the wells or boreholes by 20-25%) will lead to the
decrease of explosives consumption.
Problems
of the
rational forming and optimal classification of various off balance and lost ores in complex
structured deposits are very important from both ecological and economical
points of view.
Our recommended
method of the economical evaluation of the classification parameters for the
off balance and lost ores is based on the principle of the multicriteria optimisation,
providing differentiation and complexity of evaluation results. Implementation
of this method allows to consequently apply non-equivalent criteria what makes
it possible to simplify the complex interrelations of indicators and economical
uncertainties in the decision-making process.
Multicriterial
economical estimation is an alternating maximisation of partial criteria and
choice of the concessions dimension. Strategy of the economical estimation is
oriented to achieve the given goal and to find the best efficiency criterion
consisting of the sum of partial criteria ranged by significance.
The essence of the
method of the economical estimation is in the substantiation of several
rational partial criteria allowing to optimise parameters for separating the
off balance and lost ores in the course of the mining process. Based on principles of the multicriterial
optimisation and on peculiarities of forming different kinds of the off balance
and man- caused waste ore masses during the exploitation process as well as in
accordance with the concept of a differentiated approach to their estimation as
partial criteria applicability of the following economical criteria should be
considered: profit from the realisation of raw materials; sum of the normalised
costs and losses from the realisation of the raw materials; internal rate of
profits which is defined by comparison of sizes of discounted profits and costs
of the production; complex, including natural and economical aspects of the ecological technical decisions,
representing sizes of the dynamic income on the unit of the gross product.
These above mentioned four criteria as partial criteria of the general
multicriterial estimation are parts of the whole generalised complex-vector
criterion-playing role of the target function of the optimization. Quantitative
developing of the one vector criterion for the multicriterial economical
estimation is realised on the basis of identifying the inter-relation of the
abovementioned partial criteria that have been maximised in the course of
finding the common optimum with the help of target function (expressed as a
complex vector criterion).
The first economic
criterion is the profit from realisation of the mining off balance and
man-caused lost ores conditions efficiency from the point of view of obtaining
the maximum profit due to improving productional, technical, organisational and
other aspects of the development of the production processes of the mining; it
belongs to economical criteria. In the local system - without any respect to
the development of the process of the transition to market economy - under the
currently existing tax system and incomes distribution, the gross profit can not
serve as a sufficient indicator of the effectiveness of the plants work. The
usage of it for estimating the investment efficiency, underestimation of terms
to obtain profit as well as subjectivity of the choice of the pay-off periods
would lead to unreliable conclusions and overestimated results. Gaining the
maximum profit cannot become the main goal of the enterprise because the first
objective is to provide its vital capacity under conditions of competition and
dynamics of the demand and supply. The actual aim of the enterprise consists in
forming the minimal value of the enterprise funds. The same shortcoming has
another criterion – the profitability index expressing the ratio of the profit
in comparison with total costs.
The second
economical criterion - internal rate of return - allows to avoid necessity to
choose coefficients of discounting and to prevent from mistakes related with
these coefficients, usage of the capital costs, losses and cash inflows in the
way of summing depreciating charges and profit
got after tax deduction with taking into account additional payments and
benefits. Identification of its value is performed by integrative solving of
the equations where difference between discounted profits and costs (NPV)
equals zero:
åRV cash inflows - åPV cash outflows =
0 (1)
where: åRV cash inflows - normalised (to the present moment of time)
sum of the positive values of the cash flow;
åPV cash outflows -
normalised (to the present moment of time) sum of the negative values of cash
flow.
The acceptability of
this important criterion is also related with certain difficulties i.e. 1)
during the solving of the above-stated equation some times might appear
multiple roots what is related to the decrease of the market price on the
product or to great investments into production widening or to the costs for
the complete extraction of the ore bodies; 2) in order to take a decision about
the investment, it is anyway necessary to compare the calculated value of RR to
the normative value of the percentage rate of income (approved by the subject)
etc.
The analysis of the above-mentioned criteria acceptability results in the following recognition: the dimension of the profit does not respond to modern market conditions for taking it as a criterion of the economical efficiency of the activity of the production. Economical criteria - internal rate of return and normalised costs - as the main components of economical consequences require respective reorganisations applied to the particulars of market requirements from the point of view of the complete ores extraction.
The fourth natural
complex criterion responds more objectively to the modern requirements of
the effectiveness of the production development; as to the significance and
importance does not yield to other well-known economical criteria.
For substantiation
of the first economical criterion some positions of the abovementioned
criterion are used, that is known abroad as internal rate of return (IRR) which
in essence belongs to general discounting methods. The following analogies are
accepted: “The sum of positive values of cash flow (åPVдoх) “ – summary compensating economic effect as the income obtained due to increasing
completeness and quality of the ore extraction. “The sum of negative values of
cash flow (åPVрас)” – summary economical harm
caused by losses of value of the ore reserves leading to devaluation of common
costs including investment, credit and other investments. Differing from the
values of åPVдoх and åPVрас initial values on recommended method (used in the
method of internal rate of return - IRR) are realised in the present time
through discounting coefficients (ωi).
On the basis of
abovementioned results of analysis and on the basis of the estimation of
acceptability of the known economical criteria with taking into account
peculiarities of the off balance ores elaboration in the recommended method
following rational criteria are accepted: economical criterion defined as sum
of the economical consequences caused by mining and realisation of the off
balance and lost ores (F(Этт)) and complex natural criterion as sum of the
extracted values coming from off balance and lost ores with regard to the
significance of their impact on the efficiency
of the ore exploitation (FЦИЦ)).
The generalised
complex criterion of the multicriterial optimization of the forming off balance
and lost ores and the parameters of their division during the mining process
with regard to chosen two partial criteria is represented as:
(2)
As estimation
criterion of the optimised forming and division of the off balance ores the maximum
complex-vector sum of the economical criteria is accepted. It is obtained due
to increasing the efficiency and completeness of extraction of the deposit
reserves and due to reducing the level of harm of the extracted value, caused
by losses and impoverishing of the ore during the mining process.
The task of the
economical estimation using the chosen criterion in this case comes to the
consequent estimation and maximisation of separate partial scalar
criteria:
Estimation
SupK1(Дтт)=Ki(X); Дтт
Î Дтт
Estimation SupK2(ЦИK)=Kj(X(N)); ЦИЦ Î ЦИЦ (3)
The function Ki(X)
usually is continuously differentiated on X, and
the function Kj(X(N)) is continuous uninterrupted on the sum of
arguments. Possible maximum values of these chosen criteria appear as the
result of solving these tasks. They are optimal as to given consequences of
partial criteria.
The first economical
criterion - defined as sum of economical consequences caused by the mining process
and realisation of the types of the off balance and lost ores - stipulates all
exploitation, investment and current costs and losses originated by an
effective development of the new technologies and decisions about their
implementation. Though this criterion is commonly known as the value
criterion in relation with market
requirements its definition needs a new approach and market estimation.
Estimation of the definition of this partial criterion concludes as a sum of
economical approaches (effects) resulting from the reduction of the costs of
the optimal division of the off balance ores types. It looks like:
(4)
under
limitation functions:
k
å qiтт × Цiтт ® max
(5)
i=1
k
å qiтт × Ciтт
® min; (qiтт>0)
i=1
where: qiтт – quantity of the
i-th off balance ore (in tons); Цiтт, Ciтт - market
price and full net cost of the i-th type of the off balance ore. During the extraction of the ores deposits on the extraction
contour of the ore bodies as a rule, there is a loss of
their certain part which is inevitable under existing systems and technologies
of the deposit exploitation. This lost part
of the reserves of the rich ore appearing in the course of the process of the extraction , sorting,
transportation and ultimate forming of the ore types
of the by their economical
content represents the economical consequence as a lost extracted value. Therefore the second complex natural
criterion established to achieve the optimum of the lost part of the value extracted as a result of the mining process and of the realization of different ore types.
Estimation of this complex natural criterion - defined as summary lost value - is
expressed by means of the size of losses of the part of the rich types
ores (Пм) and
degree of the significance of their impact on the exploitation efficiency (DЗттп) and it is given by:
F(ЦИЦ)=å (Цттп +DЗттп) (6)
i
Hence
(7)
where ai - coefficient on
limitations to the technical conditions of the quality (appropr.units).
Degree of significance of economical
consequences of the lost part of the extracted value on
the efficiency of the mining process is calculated by means of the formula:
(8)
Size of the lost part of metal on all K – types
of the ore during their exploitation, sorting,
transportation and shipment is defined by direct metering.
As it follows from estimations (4) – (8), the optimal
forming and sorting of the off balance and lost ores types during their exploitation is
achieved under the conditions
F(Дтт) ® max
F(ЦИЦ) ®min
(9)
The solution of the common task of the optimal forming of the
off balance and lost ores could be presented as finding the global optimum in the multitude of the optimal solutions of the task using the linear programming under concrete variants of elements of the given
matrix within limits of the field defined by normative technical
conditions given by the consumers.
The method of the optimal sorting of the off balance and lost ores is recommended to be used when
substantiating effective technologies of the forming of different kinds of raw
materials, as well as technological solutions, oriented to
increase the completeness and quality of the reserves extraction under conditions for exploiting polytype and multi-component complex deposits.