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By Jeffrey Shawn Peterson

The testing procedures of the u.s. Mine Safety and Health Administration specify that intrinsic safety acceptance tests be conducted using a standard tungsten-cadmium electrode configuration in the break-flash apparatus. However, in realistic mining environments, other materials may be more likely sources of sparking. Information defining the probability of spark ignition between common materials such as aluminum, brass, copper, lead, tin, cold-rolled steel, and stainless steel is of more practical value in determining ignition hazards. The U.S. Bureau of Mines has completed an investigation of the influence of material on the ignition probability using the breakflash apparatus. By comparing ignition currents or ignition voltages corresponding to a probability of one ignition per thousand sparks to those found previously for cadmium, a margin of safety may be estimated for each material. This report presents the results of an investigation into the influence of disk electrode material on the probability of ignition.

Jan 1, 2010

By A. C. de Araujo, M. G. Barbosa, R. Martino, S. Gaydardzhiev

The Iron Quadrangle district is a world-class iron ore mining district in the region of Belo Horizonte, capital of Minas Gerais state, in Brazil. Many mining companies have been mining high-grade hematite ores for decades throughout the region. The mines reserves often include itabirite ores which are available in high volumes, but have lower iron grades than hematite ores and require elaborated mineral processing to meet the requirements of downstream steelmaking. Itabirite ores have acquired importance, with the depletion of high-grade hematite reserves due to their intensive mining. The objective of this paper is to propose a geometallurgical model for the processing of itabirite ores from an Iron Quadrangle deposit, which will allow predicting the behaviour of ores throughout the deposit, according to their local variations. An initial step consists in characterizing representative samples of the different ores to acquire mineralogical and textural data. Then, itabirite ores of known characteristics are processed with different techniques, in order to extract the trends and key parameters upon which the geometallurgical model is developed. At first, the model takes into account the particle size distribution and its shift during mining and screening, as well as the chemistry and mineralogy of the material. Then, using the previously identified key parameters such as iron recovery, the model predicts the composition of the processing products. Finally, this data is used to model the mineralogy and mass recovery of the products. The geometallurgical model is of great importance, as it is able to model the processing of any sampled ore throughout the deposit. The incorporation of the results in a mining block model will assist mine planning and opens new opportunities for an optimized mining schedule.

Jan 1, 2016

By G. V. Borquez

For many years drilling and blasting has been considered more of an art than a science. This is still true in some respects, but today scientific approaches to drilling and blasting design must be used to plan an efficient operation which achieves desired fragmentation within constraints. These constraints involve minimizing damage to the wall or nearby permanent structures and avoiding undesirable fragmentation and mine dilution which can adversely affect operation costs. The degree of fragmentation by blasting is the most important single factor in any attempt to optimize the overall cost of the mining operations. The mining cycle begins with the drilling and blasting operations, which result in a given blasted rock size distribution. While this operation represents only about 20% of total mining costs, the efficiency and costs of the subsequent operations are strongly dependent on the fragment distribution obtained.

Jan 1, 1986

By Manqiu Xu

"Ore grades are decreasing and ore deposits are becoming more complex. In order to make a sound economical decision about a mining project, metallurgical testwork must be carried out. A few large “representative” samples cannot represent the metallurgy of a large ore body and a large number of samples reflecting variation in ore head grades and in mineralization types must be obtained for proper metallurgical studies, including flowsheet development for a greenfield project. A relationship can be established between the recovery of valuable minerals and ore grade for each mineralization type. This relationship can be used to establish a correlation between values recoverable and values contained in the ore body that can include multiple pay metals. With this information, a sound economical decision can be made about the viability of a large mining development project.INTRODUCTIONThe demand for minerals today is historically high as many countries are being rapidly industrialized. The supply for these minerals is not necessarily running short. However, it is widely accepted that the world today is running short of the easy to mine and easy to process ore deposits. As ore grade is decreasing and ore mineralogy is becoming more complex, metallurgical testing must be fully conducted in order to make a sound economical decision about a mining project. For a high-grade and high-quality deposit, it is hard not to make a good profit even with low metal prices. For a low-grade and hard to process deposit, the profit margin is much lower and is dependent on the throughput and the recovery of valuable minerals. The recovery of valuable minerals is a function of ore grade and mineralogy and it must be experimentally determined for a given processing option.At Vale Base Metals Technology Development, metallurgical testing for an existing operation or brownfield project is termed as Ore Evaluation, while metallurgical testing for a greenfield project is termed as Flowsheet Development (Xu, 2011). In the past, metallurgical testing involved a few large composite samples for lab and pilot plant testwork. As ore deposit becomes less homogeneous and more variable, a few large composite samples cannot represent the metallurgy of a large ore body. In addition, useful information about the deposit such as zones of “impurities” or floatable rock minerals would not be obtained. Different processing strategies could have been developed if the locations and sizes of these zones were known in advance. For proper metallurgical studies, a large number of samples reflecting variation in ore head grades and in ore mineralization types must be used. A relationship can be established between the recovery of valuable minerals and ore grade for each mineralization type. This relationship can be used to estimate values recoverable in the ore body that can include multiple pay metals. Ultimately, the recovery verses ore grade relationship will be used in business decision-making."

Jan 1, 2013

By Leonard Obert

This Bur of Mines investigation considers the deformational behavior (creep) of pillars made from three quasi-plastic rocks--salt, trona, and potash ore. The first phase of this study considers the design of a model pillar suitable for creep tests; in the second phase, six model pillars prepared from salt from two sources, from trona, and from potash ore. The pillars in each group were subjected to a different but constant axial stress, and the axial strain was measured for 1,000 hours.

Jan 1, 1965

By G. M. Cresswell

The 2 360 t/h two module Phola coal preparation plant represents anew era of large plant in the Witbank coalfield designed to extend its life to 2020 and beyond. The plant uses the optimum processing model for Witbank coals, receiving a feed coal size of -50 mm, wet screening it into coarse and small coal fractions 50 x12 and 12 x0.63 mm before processing them in parallel through two primary DM cyclone sections, in order to make a 27.5 MJ/kg export floats product. The sinks are processed through a common high density DM cyclone section to produce a 21.5?23 MJ/kg thermal coal middlings product. The plant design incorporates the largest size DMS equipment used to date in South African coal preparation plants, i.e. 1 150 mm large diameter pump fed DM cyclones and 4.2 m width banana screens. The fine coal is conventionally processed by spirals, whereas the raw coal slimes are filtered using automated plate and frame filter presses and added to either the middlings or discards depending on its quality. The paper describes the database, innovative design concepts, construction, and commissioning.

Jan 1, 2010

By S. J. Jung

The stability of underground openings for deep mines is critical, since incorrect orientation or geometry of shaft, stope, and accessways often results in the failure of openings due to high stress concentrations. Current state-of-the-art procedures for the design of underground openings are largely based on rules of thumb, experience, and trial and error. Rules of thumb are invariably based on the past experience of the designer and may not remain optimal as the depth and complexity of mine workings increase. Often, as conditions change, and as the interaction between geology, in-situ stress conditions, and mine openings grows more complex, the cost of maintaining structural integrity becomes prohibitive. Existing design procedures for deep mines are rapidly becoming inadequate as mines are worked at greater depths. For example, in the Coeur d' Alene Mining District, several million dollars are spent for inspection, repair, and maintenance on a regular schedule, largely as a result of inadequate design. In these types of situations, it is of critical importance that a new design methodology be developed for the layout and design of underground openings.

Jan 1, 1994

By Catherine Johnson, Barbara Rutter

The shock tunnel located at the Missouri University of Science and Technology Experimental Mine is 65 feet 9 inches (20.0406 m) in length. The tests performed inside of this tunnel are either arena tests or shock interaction and transfer (SIT) tests. Arena tests simulate a large open air blast, with lower explosive weights, by elongating the impulse of the blast wave. SIT tests are conducted to determine how the produced shock wave interacts and transfers its energy into a target object located at the end of the tunnel. The target used in this research is multilayered, with each layer being a different material. The targets are 2 ft. by 4 ft. (0.6096m by 1.2192m) pieces of Medium Density Fiberboard (MDF), DOW polystyrene foam insulation, and gypsum drywall. The order of these materials varies with each test. This shock tunnel is unique, because the geometry changes along its length. To fully understand how the shock waves are affected by these changes, a working model was needed. The second purpose of this model is to confirm the maximum charge size of 400 grams (14.11 oz.) of C4 that can be detonated inside the tunnel without causing damage to or failure of the tunnel, thus reducing the amount of time needed in downtime and repair. The model predicts pressures in various locations both within the tunnel and the attached target, thus assisting in determining where failures would likely occur. In the process of generating this model, several problems were encountered, including filling the tunnel with air, meshing the complex geometry, and creating the tunnel in a CAD system. This paper will discuss how these problems were solved. A working model was created by using ANSYS Explicit Dynamics and ANSYS Autodyn. The tunnel geometry file was created using SolidWorks and includes the complex geometry changes along with the target and its mount located at the end of the tunnel. The results produced by the model were compared to the field SIT tests. The comparison of the results from both the model and the experimental testing showed a similar trend in the pressure traces.

Jan 1, 2018

By A M. Sardo, D E. Sinnett

This study uses the Q Method to examine how those living in former metal mining landscapes value this heritage and their preferences for the long-term management of mine waste. Such sites are often perceived as derelict or degraded, and of very little value. It is therefore assumed that their reuse, for example for development or recovery of metals, is likely to be beneficial. There are around 5,000 former metal mines in England and Wales, many of which are protected for their ecological, geological or cultural value. The Q Method is particularly suitable for issues where there is no consensus of opinion. We asked 38 residents of six mining areas in England and Wales to ‘sort’ a series of statements based on their resonance with the resident’s perspective; this is the Q sort. The statements covered a range of opinions of the mining legacy, its value and options for its management with a particular focus on the potential for metal recovery from the wastes. Analysis of the Q sorts revealed five perspectives on the mining heritage. All placed a high value on the cultural and ecological value of this heritage, however, they differed in their priorities for long-term management. For example, emphasis was placed on either nature conservation, cultural heritage, water quality or the opportunity for job creation through reworking the mines. Cutting across these themes there were also differing perspectives on the role of experts and local people in shaping the future management of the wastes. This research suggests that the views of local people are nuanced; they value their mining heritage but opinion is split on the most effective way to manage these sites especially where there is an impact on water quality.CITATION:Sinnett, D E and Sardo, A M, 2018. Former metal mining areas in England and Wales – local residents’ preferences for the management of wastes, in Proceedings Mine Waste and Tailings Stewardship Conference 2018, pp 126–134 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 23, 2018

By J. E. Allen

The trend in refractory technology for the copper and nickel industries has been to higher quality raw materials and improved processing technology. These changes have been dictated by the changes in pyrometallurgical processes in these industries. For example the introduction of flash smelting, reaction type smelting and auxiliary slag cleaning furnaces havedemanded better refractories materials. Extensive field applications and improved laboratory testing procedures have helped make this transition possible. Changes in refractory technology, primarily in basic refractories, are followed from the late fifties to the present and into the future.

Jan 1, 1994

By L. P. Srivastava

Rock bolts have been used since long to enhance the shear strength response of jointed rocks in civil and mining engineering structures. However, the assessment of strength response of a rock mass reinforced with rock bolts remains an unresolved problem till date. In the present article, an attempt has been made to study, through physical model tests, the shear strength enhancement of a blocky mass due to provision of passive rock bolts. Direct shear tests were conducted on large specimens of size 750 mm x 750 mm x 900 mm of rock mass under a normal stress varying from 0 to 2.0 MPa. Concrete was used as a model material to simulate intact rock and, elemental blocks of size 150 mm x 150 mm x 150 mm were used to form the mass specimens. Steel bolts of 6 mm diameter with 2 mm thick grout were used to reinforce the mass. Three different configurations of bolts were adopted. Observations were made on shear stress, horizontal shear displacement, and dilation during the tests. Effect of normal stress and reinforcement on peak shear stress and shear stiffness was studied. It is observed that the rock bolts enhance the shear strength of the mass by preventing sliding along the shearing plane, and by inducing additional normal stress due to tension mobilized in the bolts. The rock mass, therefore, becomes stronger due to the high degree of interlocking produced by the bolts. Shear strength of the mass increases with increasing numbers of bolts. In the case of reinforced mass, the enhancement in shear strength due to provision of bolts decreases with an increase in normal stress. The provision of bolts improves the cohesion of joints substantially. The effect on friction angle is low. The shear strength enhancement depends on the area of the bolts, spacing of the joints, spacing between the bolts and the cohesion of the intact material. A correlation has been established using which the enhancement in shear strength due to the provision of bolts can be assessed.

Jan 1, 2015

By M Grigorescu, J H. Hodgkinson, H Alehossein

A new framework that collates and interprets pre-existing data to assess vulnerability and ultimately plan to avoid or minimise flood-related risk to infrastructure, people, downtime, environment and revenue has been developed. The æClimate Related Adaptation from Terrain Evaluation ResultsÆ (CRATER) method tested at a coal mine in Queensland, provides semi-quantitative information to assist decision makers when designating investment for minimising vulnerability of mining operations to climate. Here we present the processes involved in this three-step approach that uses pre-existing spatial data of the mine site and local knowledge to build a set of visual tools to assist decision-making. The first step of the process is performing multi-criteria evaluation (MCE) within a geographic information system (GIS) on ranked natural conditions at the mine, such as elevation, slope, drainage, soil and vegetation, which is performed to identify critical flood areas. Secondly, a fault-tree analysis identifies how impact can occur and what options there are for impact reduction. Finally, a resource assessment of the mineÆs capacity to adapt reduces the adaptation options to those most suited to the mine. The results are confidential, but for the purpose of introducing the methodology, we present simplified results, particularly of steps 2 and 3. CRATER can also be used for future æwhat-ifÆ flooding scenarios to identify the most suitable locations for roads, buildings or other critical infrastructure. The methodology is transferable to any mine, series of mines or locations along the mining value chain that have sufficient data, providing a practical decision-making tool to identify æno-regretsÆ actions that not only could reduce downtime after or during an event, but in some cases may enhance production between extreme events. We now plan to test this method at a broader scale, to encompass more than one mine in the analysis.CITATION:Hodgkinson, J H, Grigorescu, M and Alehossein, H, 2013. Climate Related Adaptation from Terrain Evaluation Results (CRATER) - interpretation of pre-existing data for mine site flood vulnerability and management, in Proceedings Water in Mining 2013 , pp 259-266 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 26, 2013

By D. W. Bridges, S. R. Borrowman

Thorium and yttrium oxides were recovered from siliceous ores of the Powderhorn , Colo . , area . Processing comprised ( 1 ) acid curing and subsequent ( 2 ) acid baking , ( 3 ) leaching , and ( 4) solvent extraction of thorium , using a primary alkylamine , and yttrium , using di - 2 - ethylhexyl phosphoric acid . About 95 pct of the contained thorium and yttrium was recovered from ore containing 1.2 pct Th02 and 0.5 pct Y₂ 03. The thoria product was 99 pct Tho ; the yttria product was 77 pct Y₂ 03. A 150 - to - 1 concentration ratio was effected on the latter , but some contaminating lanthanon - group oxides remained .

Jan 1, 1964

By V. G. Medina

The 15 000 t/d La Coipa mine initiated operation in July of 1991. The complex consists of a conventional, open-pit mining operation and a mill employing cyanide leaching with Merrill-Crowe gold and silver recovery. The process plant includes a primary crushing circuit, a 15,000 t (live) covered stockpile, a semi-autogenous mill/ball mill/crusher or SABC grinding circuit, a leach circuit, a belt filtration/washing circuit, a zinc precipitation circuit and a "dry" tailing disposal system. The process plant is described in detail with major design considerations used in the selection of the processes and equipment. The unique methodology employed in the disposal of the filtered tailings is also described.

Jan 1, 1992

By W. R. Hudspeth

AS an outgrowth of its spodumene recovery operation at Kings Mountain, N. C., Foote Mineral Co. has been recovering a heavy mineral by-product. Foote leased this idle plant in 1951, reactivated it, using a new spodumene recovery process, and purchased plant and properties in October 1951. While the operation at Kings Mountain is primarily concerned with the production of spodumene concentrate, pilot plant work determined that the pegmatites also contained heavy minerals including cassiterite. Plans were made to recover the heavy minerals as a by-product and the flowsheet incorporated these facilities when the mill was modified for the new spodumene recovery process. The orebodies consist of spodumene, feldspar, quartz and mica. Apatite, tourmaline, and beryl are present in small quantities. The wall rock is pre- dominantly hornblende shist. The heavy minerals, including cassiterite, columbite, pyrrhotite, monazite, pyrite, and rutile represent about 0.2 pct of the ore. The fine-grained heavy minerals are disseminated throughout the dikes, apparently unassociated with the spodumene. The pegmatites are quarried and secondary breakage is by mud-capping and block-holing. Power shovels load into trucks transporting the ore to a coarse ore bin. A Telesmith 10x36-in. apron feeder delivers the ore to an 18x36 in. Traylor Jaw crusher adjusted to discharge -3 in. product to a primary conveyor. The conveyor delivers to a 4x5-ft Tyrock single deck vibrating screen using 3/4 in. cloth. The screen undersize is elevated to the crushed ore bin. Screen oversize goes to an Allis-Chalmers Hydrocone Crusher fitted with 4 in. concave and set to deliver approximately 66 pct minus 3/4 in. The crusher discharge returns to the primary conveyor. The crushing and screening installation has a capacity of about 60 tons per hour. Spirals The crushed ore is delivered at a rate of 350 tons per day to two 6x8-ft Hardinge Pebble Mills, equipped with 20 mesh Ton-Cap trommel screens. The screen oversize is pumped to a 12-in. hydroclone for primary desliming. The hydroclone underfl spirals. There is no heavy mineral loss in the hydro-clone overflow. The spirals bank consists of eight 5-turn Model 24-A Humphreys Spirals. The top port and the last four ports of each spiral are blanked, the remaining nine port splitters are adjusted to remove about 5 pct feed weight. The heavy mineral rougher concentrates are upgraded on a Deister Overstrom table. The spiral concentrates contain approximately 4 pct heavy mineral, and the spiral reject, which goes to another section of the plant for spodumene recovery, contains about 0.03 pct heavy mineral. There is an interesting feature in the spirals installation. An adjustable splitter mounted on the discharge boxes splits out a mica fines product containing very little heavy mineral. The mica product is cleaned by spiralling and screening. Thus the spirals recover two products; mica, and a heavy mineral rougher concentrate. Table Treatment The rougher spiral concentrate goes to a Deister Plato table, modified to receive a Deister-Overstrom No. 6 rubber cover with sand riffles. The table is operated with a 5/8 in. stroke, 270 strokes per minute, and a slope of 1/2 in. per ft from feed to tailings side. There is no slope adjustment from motion to concentrate end. Wash water consumption is relatively high, since the large spodumene grains tend to report with the fine heavy minerals. A middling band about 4 in. wide is maintained in order to produce clean concentrate. The middling, representing about 10 pct of table feed, is recirculated by air-lift. A band of concentrate grade coarse spodumene occurs just below the middling. This is removed and delivered to concentrate storage. The table tailing, containing approximately 0.7 pct heavy minerals, is returned to the spodumene feed preparation circuit. The heavy mineral table concentrates are approximately 45 pct cassiterite, 33 pct columbite, 14 pct pyrrhotite and 8 pct monazite, together, with some rutile, pyrite, and copper from blasting wire. Concentrate is collected at 24 hour intervals. and dried. If the concentrate remains in wet storage appreciably longer surface oxidation takes place which seriously interferes with the subsequent magnetic separation process. About 150 lb of heavy mineral concentrate is produced per 24 hours and shipped to the company's plant at Exton, Pa. for final separation into tin and columbium concentrates.

Jan 1, 1952

A novel, low-pressure adaptation of Praxair?s coherent jet technology utilizing CoJet lances was developed for application at Inco&apos;s Copper Cliff Smelter where oxygen is available in large tonnage quantities but only at relatively low supply pressures (< 193 kPa header pressure). The project objectives were to evaluate the effect of coherent jet technology on controlling oxygen lance accretion (?horn?) formation and to increase oxygen efficiency in the Inco Oxygen Top-Blowing Nitrogen Bottom Stirring (TBBS) MK Reactor used for converting nickel- contaminated chalcocite to semi-blister copper. This paper describes the development and subsequent implementation and testing of two CoJet lances in this application.

Jan 1, 2005

By R. O. Dannenberg

This Bureau of Mines report describes the results of research to develop a process for recovering additional beryllium from a commercial mill waste product, fluoferrate leach residue. Forty-five percent of the total beryllium in the leach residue was recovered in a beryllia product assaying over 98 pct Be0 by a process comprising (1) leaching with 1 N sulfuric acid, (2) adjusting the acidity of the leach liquor to pH 2, (3) extracting the beryllium with di-2-ethylhexyl phosphoric acid (EHPA), (4) stripping the loaded extract with sodium hydroxide solution, (5) boiling the sodium beryllate strip solution to precipitate beryllium hydroxide, and (6) calcining the beryllium hydroxide. Calculated reagent requirements per pound of Be° recovered by a proposed flowsheet were 28.1 lb sulfuric acid, 0.04 lb flocculent, 0.15 lb EHPA, 0.06 lb isodecanol (IDA), 0.22 gal kerosine, and 6.3 lb sodium hydroxide.

Jan 1, 1966

By Jie Ma, Bo Wang, Jieyu Zhang, Jian Zhao, Zheng Chen

"In this paper, solidification process of steel ingot was simulated by ProCAST software, based on cellular automaton-finite element (CAFE) model. A 22 t steel ingot was divided into continuous small zones (100x150x180 mm) in radial direction, then the temperature field, shrinkage cavity and porosity, particularly, the microstructure were simulated. The results show that: there was a columnar-to-equiaxed transition in microstructure on radial direction. Zones, closing to the center of the ingot, had a more developed and fined equiaxed zone, while zones closing to the periphery of the ingot had a more developed columnar zone. It indicated that temperature gradient has a great influence on microstructural morphology. Thus, the simulation results were highly agree with the experimental results, verifying the feasibility of this simulation method. It significantly reduces the time of simulation, and has important significance for predicting the microstructure of large steel ingot.IntroductionSolidification microstructure of steel ingot have a significant effect on the quality of the final steel products. Although many experimental works have been carried out in order to obtain the optimum condition for solidification process of continuous casting, it is also very desirable to establish mathematical models to simulate the evolution of solidification structure. The simulation methods can be divided into deterministic models and stochastic models, which have been developed rapidly over the last couple of decades. Cellular automaton method is one of the stochastic models. Rappaz and Gandin [1, 2], Nasatac and Stefanescu [3, 4] are the earliest researchers engaged in the this field. Moreover, Rappaz and Gandin simulated the solidification structure and CET (columnar grain to equiaxed grain transition) of metals using the CAFE method (cellular automaton-finite element method) for the first time [1, 2]. Recently, the CA (cellular automaton) model also considered the effects of fluid flow on the solidification process. Zhu, et al. [5-11] improved method of CA , they used the KGT model to describe the undercooling needed during the growth of the dendrite tip."

Jan 1, 2014

By Sunil Tripathy, Y. Rama, Srinivasulu. A., Amit Ranjan

Process improvements in an operating plant are always challenging. Mineral beneficiation plants based on gravity concentration techniques need continuous evaluation and monitoring of its processes for getting maximum recovery and better grades. But, in an operating plant it is very difficult to control all the parameters due to numerous reasons such as unsteady operation, fluctuation in the quality of run-off-mine ore, overall flow rate etc. For better understanding of the beneficiation circuit, it is necessary to evaluate the critical operating parameters which affect the performance in terms of grade, recovery and throughput including losses of valuable materials into tailing. Accurate data collection and proper data interpretation followed by making necessary change which is implementable in an operating plant play very critical role in performance of the circuit. In case of gravity operated beneficiation circuits of chrome ores where the quality of the feed and physical parameters varies continuously, the operators are required to modify the critical operating process parameters on continuous basis which is very difficult and tiresome. There are many causes of the data variability, including both error (sampling and assay), and real variation in performance due to changes in ore mineralogy, operating conditions and other factors. In this article, attempts made to evaluate the performance of ultra-fine beneficiation circuit in terms of silica reduction in the concentrate of chrome ore beneficiation plant (COB), India are discussed. The approach adopted and practical problems encountered during the study were also discussed. Results obtained from plant audit based on the above methodology has shown that SiO2 content in the concentrate can be reduced to <4%.

Jan 1, 2014

By Bernadette C. Michalski

Mineral raw materials, labor, capital, and technology form the basis of industrial production. The augmentation of one or all of the elements--labor, capital, and technology--will result in industrial growth. Thus, an increase in the labor force would increase output. A similar result would be achieved by expanding capital investment and supplying labor with more equipment. Finally, industrial growth can be achieved by introducing more productive methods and techniques born of technological advancement. The Soviet Union has employed these elements in many patterns to catapult from an agricultural to an industrial economy in four decades. The early history of the Soviet Union was marked by limited capital and borrowed technology, forcing the Soviets to concentrate on an abundant labor reserve to support the industrial program. The source of this reserve was the rural population. In [1928], 80 percent of the working population was employed in agriculture. This figure dropped to 43 percent by 1956, whereas industrial employment in the same period increased from 8 to 31 percent.3/

Jan 1, 1960