共查询到20条相似文献，搜索用时 31 毫秒
1.
| 1. |
Cavity elimination technology by isolation and filling with low-strength materials has been used successfully in working mineral
resources by underground mines, including beds of complex structure.
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| 2. |
The technicoeconomic and social effectiveness of cavity elimination that preserves the surface of the earth and the environmental
setting in the area surrounding the mines and the utilization of production wastes and low-quality local mineral resources
endow these technologies with a conservation-oriented value and open new prospects for their use.
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| 3. |
Scientific and engineering principles of resource-saving cavity elimination technologies and years of practical experience
with them should be considered by designers of plans for development of new deposits in mining fields across the country.
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| 4. |
Tested methods of material quality improvement are recommended for large-scale introduction in mining and related industries:
| – |
disintegrator processes of material grinding and activation;
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vibration equipment for sorting, triturating, and transporting granular and fluid mixtures; and
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electrochemical water treatment with membrane technologies.
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相似文献
2.
| 1. |
The main criterion which determines the effectiveness of selective comminution is the ratio between the energy of the grinding
bodies and the energy required to break particles of the weak component of maximum size, and particles of the strong component
of the minimum size. The maximum effectiveness of selective comminution is achieved in cases of operating with energy combinations
(3), (11), and (13).
|
| 2. |
With selective comminution of a two-component mineral mixture in accord with energy combinations (3), (11), and (13) the relative
comminution rate of the strong component increases uniformly, but it decreases for the weak component. Grindability of the
strong component decreases in relation to individual grinding of it, but for the weak component it increases in relation to
its individual grinding.
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| 3. |
In order to describe comminution kinetics for mineral mixtures it is necessary to develop an equation which specifies the
decreasing-increasing nature of the relative grindability of the residue, and an approximate calculation can be made using
known equations which specify either a decreasing or an increasing nature for grindability of the residue.
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| 4. |
The average size of the strong component particles affects the grindability of the weak component. With an increase in average
size of strong component particles with a change-over from energy combinations (3) and (11) to combination (13) the comminution
rate for the weak component increases.
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IGKhS, Lyubertsy. Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 3, pp. 35–41, May–June,
1991. 相似文献
3.
| 1. |
The sufficiently high reliability of the standard (k-ε) model for the Reynolds-stress in calculating the velocity field in
plane chamber-like mine workings has been demonstrated.
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| 2. |
A version of the velocity-field calculation in plane chambers by the Smagorinskii model has been proposed, using the (k-ε)
model in the preliminary stage, so as to permit considerable reduction in computer time.
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| 3. |
The most rational finite-difference schemes for approximation of the advection term in the turbulent-diffusion equation when
estimating the air transfer in plane chamber-like workings have been recommended:
| a) |
for periodically acting localized sources of impurity ejection, scheme VII (Table 2);
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| b) |
for discharge emissions of harmful impurities, scheme VI (Table 2).
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| 4. |
It is shown that scheme V (Table 2) has high schematic viscosity in a nonuniform velocity field, and therefore cannot be used
to calculate flows in chambers with complex geometry.
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| 5. |
Using the numerical modeling of the physical fields (air velocity and impurity concentration) in a ventilated volume proposed
here permits the determination either of the time to achieve the maximum permissible concentration with specified contamination-source
intensities and air flow rates or the air flow rate required in a specified ventilation time.
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S. M. Kirov Mining Institute, Academy of Sciences of the USSR, Kazan’ Branch, Apatity. Translated from Fiziko-Tekhnicheskie
Problemy Razrabotki Poleznykh Iskopaemykh, No. 1, pp. 74–88, January–February, 1990. 相似文献
4.
| 1. |
The technical parameters of coals of the grades K and K2 have been studied during working of the excavation pillar by eastern long-wall faces 4 and 5.
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| 2. |
Statistical characteristics of variation series were obtained.
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| 3. |
Maps of isolines representing the “principal relief forms” have been compiled, which describe the regularities of distribution
of the technical parameters.
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| 4. |
The variations of these parameters were examined in three directions relative to the axis of the well used for multiple hydraulic
treatment of a predegassed seam.
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Moscow Institute of Mining. Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Polyznykh Iskopaemykh, No. 6, pp. 84–91,
November–December, 1990. 相似文献
7.
| 1. |
Electromechanical regime observations in North Ural bauxite deposits can be used to evaluate the transcritical strain in rocks,
such as loosening or pillar breakage under long-term loads.
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| 2. |
In conditions where no discontinuities of rocks in the peripheral zone of workings are observed, electrometric technology
can evaluate moisture content variations.
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| 3. |
With the existing technology, it is impossible to estimte elastic strain by electrometric measurements in North Ural bauxite
deposits.
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Ural Scientific-Research Institute of Copper Production, Sverdlovsk. Translated from Fiziko-Tekhnicheskie Problemy Razrabotki
Poleznykh Iskopaemykh, No. 6, pp. 92–98, November–December, 1989. 相似文献
8.
Pre-cementation or pre-grouting of deep shafts in South Africa is an established technique to improve safety and reduce water
ingress during shaft sinking. The recent completion of several pre-cementation projects for shafts deeper than 1000m has once
again highlighted the effectiveness of pre-grouting of shafts utilizing deep slimline boreholes and incorporating wireline
technique for drilling and conventional deep borehole grouting techniques for pre-cementation.
Pre-cementation of deep shaft will:
| (i) |
Increase the safety of shaft sinking operation
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| (ii) |
Minimize water and gas inflow during shaft sinking
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| (iii) |
Minimize the time lost due to additional grouting operations during sinking of the shaft and hence minimize costly delays
and standing time of shaft sinking crews and equipment.
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| (iv) |
Provide detailed information of the geology of the proposed shaft site. Informations on anomalies, dykes, faults as well as
reef (gold bearing conglomerates) intersections can be obtained from the evaluation of cores of the pre-cementation boreholes.
|
| (v) |
Provide improved rock strength for excavations in the immediate vicinity of the shaft area.
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相似文献
9.
Spherical balls are the dominant grinding media used in ball mills. However, balls which are initially spherical, wear into non-spherical fragments. The proportion of worn, non-spherical balls in the charge of a mill fed with 50 mm balls is dominant in ball sizes less than 30 mm. Their effects on mill performance in terms of material breakage are not yet established.The variations of specific rate of breakage with single size feed and fractional filling U, were studied for the two media shapes (spherical and worn balls). Higher breakage rates were noted with spherical media than worn balls but the differences narrow with decreasing feed size and increasing material fractional filling, U. 相似文献
10.
| 1. |
With low-temperature plasma it is possible to create facings in soft rocks covering the entire working perimeter in a short
period of time.
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| 2. |
Field tests of facing models show them to have a sufficient carrying capacity and resistance to dynamic as well as static
loads.
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| 3. |
Laboratory tests of specimens from thermally reinforced clay rocks determined the dynamics of the variation of their strenth
characteristics as a function of the speed of loading.
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Military Engineering Academy, Togliatti. Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No.
2, pp. 74–78, March–April, 1989. 相似文献
11.
| 1. |
By analyzing the formation of brines in underground leaching chambers, it is shown that the general criterial dependence representing
this process includes the criteria Pz, Ku, and the geometrical simplex D/h.
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| 2. |
The authors determine the conditions of similarity for modeling the processes of brine formation in underground leaching chambers
by means of specimens of core material.
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相似文献
12.
| 1. |
A new model is suggested with simple techniques representing the dynamic behavior of an assembled support system at intersections
of horizontal mine workings. Plastic behavior of the material at the conjugation points of structural elements is taken into
account.
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| 2. |
Equations systems are formulated to calculate the behavior of a support system sustaining static and dynamic rock pressures.
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| 3. |
In case of a dynamic impact upon the support system at a conjugation, the greatest strength is attained when the rigidity
of the external medium is higher than that of the medium filling the space between the support systems of the individual workings.
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| 4. |
When a plane wave acts upon the support system at the conjugation, the internal support system removed from the wavefront
at the initial time is especially susceptible to breakdown.
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| 5. |
Support systems interact not only in terms of vibration amplitude but also vibration frequency and form. The influence of
internal support systems upon the external support system is particularly strong.
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Institute of Mathematics and Mechanics, Academy of Sciences of the Kazak SSSR, Alma-Ata. Translated from Fiziko-Tekhnicheskie
Problemy Razrabotki Poleznykh Iskopaemykh, No. 3, pp. 6–12, May–June, 1990. 相似文献
13.
The hydrogeomechanical problems of mining are considered, which deal with rocks and ground water as a single mechanical system.
Among these problems are the openpits slopes stability, rocks consolidation and surface subsidence due to ground water level
lowering, water inrushes into mine workings, rock bursts prevention by using the water injection into the advance boreholes,
etc. The paper contains the basic theoretical grounds, as well as in-situ and laboratory methods for the investigation of
these processes.
The combined study of ground water regime and rock deformations has resulted in the theoretical substantiation of the hydrodynamic
and geomechanical processes within the scope of unique scientific direction-hydrogeomechanics (Mironenko, 1974). The hydrogeomechanical
models are widely used now for the analysis and forecasting the extremely important processes connected with the safe and
efficient mining operations, as well as with the protection of geological medium. Among these processes are:
| – |
o deformations of the open-pit slopes and spoil dumps;
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| – |
o consolidation of rocks due to the ground-water pressure drop;
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o water-and-rock material inrushes into mine workings caused by deformations of the undermined rock mass;
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| – |
o geodynamical processes due to the changes in ground water regime;
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| – |
o artificial hydrofracturing in rocks;
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| – |
o transformations of clay linings under the tailing ponds and other technical water basins
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相似文献
14.
Conclusions
| 1. |
For the example of sinusoidal pulses applied to the end of a pipe, we have shown that a pulse with the greatest amplitude
at fixed shock energy will drive the pipe furthest into the ground.
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| 2. |
Other conditions being equal, the greatest distance to which the pipe is driven in the ground is directly proportional to
the amplitude of the initial pulse applied to the end of the pipe.
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| 3. |
The residual strain (stress) in the pipe due to the presence of external friction increases with the length of the shock pulse.
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| 4. |
The damping of the shock-pulse amplitude is linear, regardless of the elastic properties of the ground, as long as individual
sections of the pipe slip relative to the ground. The damping coefficient is directly proportional to the frictional coefficient
of the pipe in the ground and does not depend on the shock-pulse configuration.
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| 5. |
Analysis shows that the distance to which the pipe is driven in the ground may be increased by a factor of more than 1.5,
at constant shock energy, by eliminating the intermediate mass from the model of the shock-pulse generator; in practice, the
intermediate mass corresponds to the housing of the shock machine rigidly connected to the anvil.
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Institute of Mining, Siberian Branch, Russian Academy of Sciences, Novosibirsk. Translated from Fiziko-Tekhnicheskie Problemy
Razrabotki Poleznykh Iskopaemykh, No. 2, pp. 48–58, March–April, 1998. 相似文献
15.
During the 1990s, passive treatment technology was introduced to the United Kingdom (UK). Early hesitancy on the part of regulators
and practitioners was rapidly overcome, at least for net-alkaline mine waters, so that passive treatment is now the technology
of choice for the long-term remediation of such discharges, wherever land availability is not unduly limiting. Six types of
passive systems are now being used in the UK for mine water treatment:
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♦ aerobic, surface flow wetlands (reed-beds);
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♦ anaerobic, compost wetlands with significant surface flow;
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♦ mixed compost/limestone systems, with predominatly subsurface flow (so-calledReducing andAlkalinityProducingSystems (RAPS));
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| – |
♦ subsurface reactive barriers to treat acidic, metalliferous ground waters;
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| – |
♦ closed-system limestone dissolution systems for zinc removal from alkaline waters;
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| – |
♦ roughing filters for treating ferruginous mine waters where land availability is limited.
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Each of these technologies is appropriate for a different kind of mine water, or for specific hydraulic circumstances. The
degree to which each type of system can be considered “proven technology” corresponds to the order in which they are listed
above. Many of these passive systems have become foci for detailed scientific research, as part of a $1.5M European Commission
project running from 2000 to 2003. 相似文献
16.
| 1. |
The distribution of lumps by mass is a complementary structural-statistical lumpiness characteristic that makes it possible
to ascertain more clearly certain laws governing the process of fragment formation as compared with the distribution of lumps
by size.
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| 2. |
A Weibull-type equation provides good approximation of unimodal curves of mass distribution for the different conditions considered
for the multiple fracture of rigid bodies.
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| 3. |
There are characteristic points about which values of the distribution-shape parameter are grouped: the shape parameter is
close to 1/3 for the impact failure of lumps and the crushing of specimens, and to 1/2 for the case of explosive crushing.
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| 4. |
An increasing in the end surcharge of tubular rock specimens failed by blasting leads to a reduction in the shape parameter
for the fine fractions and to diminution of the bimodality effect.
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| 5. |
Use of the operation of the additional opening of blast-induced cracks in weakened lumps of semimetallic ore is reflected
in geometrically similar transformations of the distribution curves in the direction of a reduction in lump mass.
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| 6. |
As applies to the blast-induced failure of brittle plates, a functional relationship between the mass of the fragments and
the reduced distance to the blast center is obtained by statistical averaging; for small values of the argument, the latter
is approximated by the fourth power of the reduced distance.
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I. I. Polzunov Branch of the Altai Polytechnic Institute, Biisk. Translated from Fiziko-Tekhnicheskie Problemy Razrabotki
Poleznykh Iskopaemykh, No. 1, pp. 34–38, January–February, 1989. 相似文献
17.
Most concentrators desire to operate under optimal design configuration that guarantees high mineral recovery and low operational costs. The optimal design configurations are determined through studying the material to be milled in a laboratory mill under standard conditions. This is achieved through determining the selection and breakage function parameters and applying the mathematical simulation of the grinding process in order to optimize the size reduction process. The desired particle size is determined by the downstream processes, in our case, flotation. To this end, three mono-size classes feeds 850–600 μm, 600–425 μm and 425–300 μm of a platinum ore were ground using three different ball sizes (10, 20 and 30 mm) in a laboratory mill for the grinding times 0.5, 1, 2, 4, 8, 15 and 30 min. The data collected was used to determine breakage and some of the selection function parameters. The remaining parameters were back-calculated within the population balance model framework. The parameters were then used to obtain the product size distribution (PSD) that was later compared with the experimentally measured one. The milling kinetics for the desired size class for flotation was also simulated.There was a good match between the predicted and the experimentally measured PSD. The results of the milling done for further 60, 90, 120 and 240 min to validate the simulated milling kinetics from the determined parameters also showed good match between the simulated and the experimental one. This further confirms the validity of the determined parameters. From this, it becomes possible to determine the grinding conditions for optimal flotation. 相似文献
18.
| 1. |
The authors show the dependence of the electrochemical properties of magnetite on the thickness of the layer removed from
the specimen surface; this is of scientific interest, because the results obtained enable one to determine the effective conditions
for preparation of solid electrolytes and to refine the experimental procedure so as to obtain reproducible data.
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| 2. |
The variation of the magnetite electrode potential with the pH of the medium practically follows the same pattern as that
characterizing magnetite-hematite equilibrium.
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| 3. |
Addition of sodium oleate shifts the electrode potential toward the more negative region as a result of adsorption of the
flotation reagent, the maximum change in potential being observed at pH 6–7, which also corresponds to maximum flotability
of magnetite.
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相似文献
19.
| 1. |
The experiments that we conducted made it possible to ascertain the significant variation in the deformation and rheologic
properties of a fissured mass as compared with the monolith. The crack frequency, the number of jointing systems, the strength
and deformation properties of the monolith, and the magnitude of the effective stresses exert an influence on the degree of
variation in these parameters.
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| 2. |
In designing systems of excavations and calculating the expected deformations of the rock mass in mine workings, it is necessary
to consider not only the strength reduction, but also the variation in its rheologic properties.
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| 3. |
The investigation of the mechanical properties of a fissured mass on models of equivalent materials provides for adequate
prediction of the properties of the actual mass.
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National Scientific-Research Institute of Mine Surveying, Leningrad. Translated from Fiziko-tekhnicheskie Problemy Razrabotki
Poleznykh Iskopaemykh, No. 5, pp. 15–20, September–October, 1990. 相似文献
20.
Conclusions
| 1. |
The ultimate size of bubbles in a flotation cell is an outcome of competing processes: coalescence of bubbles and adsorption
of the surfactant on their surface.
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| 2. |
Formation of highly developed initial interface due to breakup of the gas phase is an indispensable condition for stabilizing
bubble size at a lower size level.
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| 3. |
The optimal method of frothing agent injection (for stabilizing bubble size) into the flotation cell is to inject it into
the air phase as vapors or aerosols.
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Institute of Mining, Siberian Branch, Russian Academy of Sciences, Novosibirsk. Translated from Fiziko-Tekhnicheskie Problemy
Razrabotki Poleznykh Iskopaemykh, Vol. 34, No. 3, pp.101–107, May–June, 1998. 相似文献
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