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By James A. Clem

Approximately 2000 years ago, the Lord admonished the scribes (lawyers) and pharisees (religious leaders of that time) that they had paid the tithe but had omitted the weightier matters of law, judgment, mercy, and faith. (Matt. 23:23) I want to talk about "The Weightier Matters of Law." In a situation where big government is trying to have an effect on even small details of a work activity, otherwise simple situations become complex. Regulations are written to such detail that constant compliance with strict interpretations can be a nightmare-not to mention off the target of the intended purpose for the regulation. One soon recognizes the onerous characteristics of federal statutes. Another admonition the Lord gave those lawyers and pharisees back then was that they tended to strain at a gnat and swallow a camel! He meant that the pharisees were given to devoting themselves to the strict interpretation of law by writing hundreds of subrules or interpretation to law. In doing so they eventually lost sight of the original purpose of the law. I think they were being told, keep the law-but don't neglect to humanize it Keep it simple Recognize the purpose of why the law. "Mix in" a common sense approach. Someone once said, "Common sense is instinct -enough of it is genius." Today, as 2000 years ago, we need more "genius" displayed by legislators in considering the weightier matters of law. First of all true legislature genius calls for a declarative statement about the purpose of the statute and a fair, objective analysis of the ground rules by which it will be implemented. In the Health & Safety Act of 1969, the "findings and purpose" as set forth in Section 2 do define its purpose. I believe most of us affected can be in accord with the reasons advanced for the legislation. However, beyond those well-intentioned few paragraphs, we very quickly run into trouble. Congress complicated the simplicity of the statement of purpose by mandating government intervention into areas that cannot be effectively legislated, nor even should be legislated. The Act provided for broad gaged regulation which is unnecessary, inappropriate, and tremendously costly. Frankly, it detracts from a constructive, cooperative effort by the parties involved. These are strong negatives which characterize inappropriate legislation. Appropriate legislation and subsequent regulation, which is realistically conceived and practically enforced must be born of an honest desire for improvement, based on a working knowledge of common problems which are thoughtfully analyzed. Then the legislation must be written in clear concise language so that there can be little or no doubt as to its literal meaning and intent. To be practically enforced, it must be understood by all who will enforce it and by all who are subject to it. That is to say, an effective law or standard cannot be fixed or inflexible so that it cannot be tempered in human judgment. There must be an elasticity in the statute to provide for consideration of all of the relevant facts of a given situation. Such elasticity makes the compliance effort as meaningful as it can be for the time and dollars invested. Meaningful compliance requires room for common sense. Today, we in business along with our associates in government and labor, urgently need to pause, and assess our current situation. The problems arising from the 1969 Act have been intensified through the Mine Safety & Health Act of 1977. After reading the "findings and purpose" of this legislation, and by process of elimination, we should all clearly see what is and is not the purpose of the Act. 1) It is not to turn the management of private industry over to government. 2) It is not to impair the efficient operation of business. 3) It is not to reduce productivity and profits. 4) It is not to reduce national unemployment. 5) It is not to perpetuate the bureaucracy. 6) It is not to increase the tax burden on an already overburdened people. 7) It is not to increase our balance of payments deficit. 9) It is not to replace management/labor relations in working together to solve problems.

Jan 1, 1981

INTRODUCTION The mineral sample is the fundamental unit upon which the mineral appraisal is built. Values derived from the sample are the most important quantitative measurements made in the total evaluation process. The sample value

Jan 1, 1980

By R. O. Burt

The economics of recovering slimes by gravity concentration, except in a few highly specialized cases, was hampered by the lack of suit- able high capacity equipment. However, in the last decade increasing cost of power and reagents, coupled with the development of high capacity units, has led to a reappraisal of the benefits of slime gravity concentration. This paper seeks to analyze the merits of gravity concentration, and the constraints placed upon it by the laws of motion. It traces the recent developments of unit processes, and their application to a wide range of minerals. The economics of gravity concentration are also discussed.

Jan 1, 1980

By Richard Klimpel

In this paper various formulae are developed which can be used to estimate stream flow rates or weight ratios given information on the stream components. The type and level of experimental error present in the stream component analyses does have an important bearing on the numerical values (and reliability) of the weight ratios calculated by the various formulae. A simple but theoretically sound method is shown for selecting appropriate estimation formulae for any given engineering operation. The derived formulae are applied to sets of experimental classification data for illustration purposes.

Jan 1, 1980

INTRODUCTION TO SAMPLING THEORY Before specifically discussing mineral sampling and sampling procedures, let us briefly consider broader and more universal concepts of modem sampling theory. A sample is de- fined as a representative part or a single item from a larger whole, being drawn for purpose of inspection or shown as evidence of quality. In modem theory the sample is a part of a statistical population whose properties are studied to gain information about the whole. The theory of sampling is built around the concept that if enough representative units of a larger overall population are selected without bias, the average value of the units will approximate that of the total population. Modem theory attempts to answer the question of how many samples are enough, given certain limits and constraints, and seeks to apply methods of sample selection and of estimation that provide, at the lowest possible cost, estimates that are precise enough for the purposes at issue. In order to meet these objectives the designer of a sample survey must rely heavily upon statistical theory. Statistics has been defined as the collection, presentation, analysis, and interpretation of numerical data. Statistical methods are primarily concerned with making valid inferences about a population based upon samples taken from the population. For most statistical applications, the total sample is in terms of number of items, attributes, or things; whereas mineral samples are usually in terms of weight or volume of mineral particles. Certain steps are involved in a well designed sample survey without regard to the particular field of application. Because the desired characteristics of an unmined mineral deposit can- not be known other than by sampling, we will consider these principle steps in terms of a mineral sample survey: 1) Clear definition of the objectives of the survey. In the case of mineral sampling this step is so apparent as to be almost ridiculous. However, it is surprising how often the overall objective of a sampling program is overlooked when decisions are made on a day-today basis. 2) Definition of the population to be sampled. The word population is used to designate the aggregate from which the sample is chosen. A sampling program may be designed to determine the grade of a single stope within a mine, the grade of a particular zone within a complex ore body, or the total value and extent of a mineral deposit. Since mineral sampling is usually done in phases, it is well to

Jan 1, 1980

By Takahide Wakamatsu, Yoshiaki Numata, Charn Hoon Park

INTRODUCTION A technique is needed to apply the flotation method successfully to apply the flotation method successfully to low grade and complex ore bearing hard-to-float oxide minerals. Thus it is necessary to find a new selective, powerful collector or to develop a new flotation process. Some attempts to use two or more kinds of collectors combined in flotation have been made but the principle of the reaction between the collectors used and the surface of mineral as well as the effect of combined collectors on flotation has not yet been fully understood. As part of the study on the improvement of selective collection in flotation, we have been investigating the flotation of minerals using two kinds of organic reagents, one of which is a conventional collector. We found xanthates were able to adsorb even onto the surface of oxide mineral, with the help of another organic reagent, e.g. a chelate compound (1). Furthermore, a notable effect of combined reagents such as the xanthate-amino acid combination (2) was found on the reagent adsorption phenomena and the collection phenomena, depending on the combination of reagents. The present study was carried out to clarify the effects of adding two kinds of collectors to the collection of mineral in flotation in the following two cases: (1) joint use of xanthate and di-alkyl dithiophosphate for galena collection and (2) joint use of a cationic collector with xanthate for scheelite collection.

Jan 1, 1980

By K. H. Nimerick, B. E. Scott, F. J. Beafore

A unique freeze conditioning agent (FCA) which functions by forming structurally weak ice rather than suppressing the freezing point of water has been successful in alleviating frozen coal problems. Frozen coal treated with FCA has been quickly unloaded at temperatures below -17.8OC (O°F). Other applications of FCA include deicing: conveyor belts, idler, idler arms, and other moving parts that have been impeded by ice.

Jan 1, 1980

By C. A. Shook, W. H. W. Husband, D. B. Haas

Introduction Although previous studies1,2,3 have been made, no correlations for pressure drop have been proposed. This is probably because severe particle breakage occurred and pressure drops changed substantially with time. A quantitative statement of the relationship of pressure drop to the parameters of the system is desirable for lignite since, unlike higher rank coals, lignite slurries are thixotropic. The present investigation was undertaken to quantify the pipeline behavior and required continuous monitoring of pressure drop and size distribution.

Jan 1, 1980

By D. A. Augenstein, L. V. Amundson

Operators of coal preparation plants use equipment such as large-capacity dump trucks and bulldozers to haul, spread, and compact refuse material to conform to federal and state regulations governing the disposal of solid waste. For example, federal regulations require that refuse be spread and compacted in layers not more than 0.6 m (2 ft) thick. If the refuse layers or piles have poor load-bearing characteristics, movement of equipment over them becomes extremely difficult. The increasing cost and limited space for the construction of settling ponds extensively used for fine refuse disposal are leading to the growing practice of dewatering the fine refuse by means of vacuum disk filters and combining the resulting filter cake with coarse refuse for waste bank disposal. However, this filter cake usually contains more than 25% moisture. Therefore, when it is combined with coarse refuse, the moisture level of the total refuse may become high enough to impair the load-bearing strength of the refuse. Precisely this problem and the attendant difficulties of moving heavy equipment arose when vacuum disk filters were installed at a preparation plant in West Virginia. Combining the moist filter cake with the coarse refuse generally results in a 12% moisture level for the total refuse at this plant. At this moisture level, the refuse can still be handled with some dif¬ficulty by the equipment. However, the problem has frequently been compounded after rains. The experimental program described in this paper tested the following methods of improving the load-bearing properties of coal refuse: moisture reduction, addition of crushed coarse refuse, addition of fly ash, addition of lime, and addition of a mixture of lime and fly ash. In terms of a balance between economic and technical considerations, the most effective method was demonstrated by laboratory and plant tests to be a 2% to 5% addition of lime. Test Program During formulation of a test program aimed at improving coal refuse stability, a number of treatment techniques were selected for evaluation of their effect on refuse load-bearing characteristics. The reduction of refuse moisture was the first technique considered, since moisture content plays a key role in the bearing strength of a bulk solid. The reasoning was that a very small reduction in refuse moisture, provided it could be accomplished with minimal effort and cost, would be sufficient for eliminating refuse disposal problems most of the time. At the same time, it was recognized that periods of rainy weather would offset moisture-reduction measures. Other techniques selected for evaluation because of their potential for improving refuse-bearing strength at reasonable cost were: addition of crushed coarse refuse, the addition of fly ash, and the addition of lime. A simple one-dimensional laboratory compaction test was designed for evaluating the effect of each of these techniques on refuse-bearing strength. Those techniques that gave best results in the laboratory would then be tested in the preparation plant in West Virginia. Laboratory Tests The laboratory test for evaluating each of the techniques involved the application of weight to a load module placed on a refuse sample in a container. The distance the load module sank with an increasing amount of applied weight was measured, and the relationship between module displacement and loading was obtained. The refuse container was large enough to minimize the influence of wall effects, and to decrease the effect of the container bottom, a test was terminated when the load module sank to about three fourths the depth of the container. Initially, an attempt was made to conduct compaction experiments with samples of total plant refuse. However, the presence of + 0.13 m (+ 5 in.) material in the refuse interfered with the mechanics of the test, and the large amount of material required for a representative sample made testing extremely tedious and time-consuming. To avoid this problem and because it was believed that only the fine components of the refuse were the major cause of the stability problem, tests were conducted with 13 mm X 0 (1/2 in. X 0) material from the total plant refuse. The equipment consisted of a 0.46 m (18 in.) cubic container, a loading module with 62 cm2 loading area, weights totaling 450 kg, and a portable concrete mixer for combining water and additives with the refuse. Refuse samples of about 110 kg dry weight were used for each test. Experimental compaction test data were evaluated by plotting the linear displacement of the load module vs. loading. During compaction tests, the vertical displacement of the load module was measured at each loading value. The plot of

Jan 1, 1980

By M. P. Sidorova, D. A. Fridrikhsherg

The surface charge, electrokinetic potential and surface conductance were studied for silica, alumina and rutile as the functions of PH and concentration of 1-1 electrolyte solutions. The adsorption potentials of potential-determining and specifically adsorbed ions were calculated from isoelectric and zero charge points on the basis of Stern equation and thermodynamic description. From surface conductance and charge data the mean ionic mobilities in double layer were estimated. The results give some information about the real structure of oxide-electrolyte interface and gel-layer concept.

Jan 1, 1980

By Alan D. Randolph

INTRODUCTION The production of fines is an unwanted side-effect in most crystallization processes. The definition of “fines" is relative to the size of the desired product and varies from <30 mesh for coarse KC1 fertilizers to subsieve organic material produced by salting-out pro- cesses. Sometimes a well-developed fines distribution is necessary in the production of large crystals, e.g. the fines removal stream from a potash crystallizer. The production of fines is usually not desired in a crystallization separation step. However, product purity can either improve or degenerate with a decrease in crystal size depending on the relative importance of product washing vs mother liquor occlusions in determining over-all purity. Typically, both washing efficiency and mother liquor occlusions decrease with decreasing particle size. Fine crystal distributions have historically been difficult to measure and categorize; however this situation is changing rapidly with the use of electronic particle counters of the electrical zone- sensing or light scattering type. In fact, fine-crystal measurement is perhaps the key to better understanding and control of coarse- crystal crystallization processes. The fine-crystal distribution carries much useful information from which nucleation and growth rates can be inferred. The purpose of this paper is to briefly discuss a few crystallization processes in which production and/or measurement of fines is important and to categorize the process conditions which yield a fine- crystal product.

Jan 1, 1980

By A. G. Willard

Quantification of size, shape and composition has been one of the more difficult areas for those concerned with fine particle processing of coal.&apos; Image analysers fed by optical microscopes and by scanning electron microscopes possessing backscatter detectors and energy dispersive facilities now offer techniques to improve the speed and precision of previous methods. This paper discusses the methodology and procedural difficulties associated with the microanalysis of coal. Photographs show display quality on the image analyser monitor and the equipment mentioned. Data illustrating several of the procedures are included. The major portion of data for design and operation of plant for fine particle processing depends on information regarding size, shape and composition of granular material. The lower limits of particle sizes become more important as lower grade deposits are mined. Because of the trends towards treatment of finer materials, the use of image analysis offers advantages in time, effort and accuracy. As energy becomes more critical, the above applies especially to coal processing. The Zeiss Microvideomat 2, a leading member of the second generation instruments, is now available for image analysis. There is a precision television scanning system with monochrome camera, display, control panel and central processor (see Figure 1).

Jan 1, 1980

By Noel W. Kirshenbaum, George A. Pouska, James M. Link

Literally millions of words have been written on the subject of mineral slurry pipelining. The sheer bulk of literature on the subject should be enough to convince the interested observer that the method is both viable and widely applied. It is the intent of this paper to examine typical mineral slurry applications. This examination should reveal the reasons that the slurry system was selected over other transport modes and it should provide a framework for determining the applicability of the technique to new projects. Slurry transport involves the conveyance of solid particles by suspension in a moving liquid. Almost any combination of solids in liquids may be imagined, and the conduit may be an open channel or a closed pipe. Historically, the most numerous slurry transport applications consisted of mineral particles in water. However, current research investigations are emphasizing other liquid carriers, specifically those which have greater economic value. Among these are gaseous and liquid fuels and chemical feedstocks. Another area being investigated involves the use of the pipeline as a chemical reactor system. The long residence time and turbulent flow characteristics of the pipeline make it particularly attractive for certain chemical reactions. Because these new systems involve a valuable liquid as well as a valuable solid, there is increased attention to solid-liquid

Jan 1, 1980

INTRODUCTION Much discussion has been generated over the years among geologists and engineers as to the ideal drill-hole configuration and spacing for evaluating various types of mineral deposits. Little can be found in the literature about the outcome of the programs, probably because of their subjective nature and the then lack of suitable means of scientific testing. In years past the drilling patterns and sequence were almost entirely determined by the experience and personal bias of the senior engineer, geologist, or project manager on the job. However, planning a drilling program- spacing, pattern, sequencing, etc.-is simply a specific case of sample design, or the design of a sampling program. Having been exposed in the preceding chapter to the theory of regionalized variables, and having learned something about the tools for measuring correlation, or lack of correlation, among samples within a given mineralogical population, we are now prepared to apply these concepts and new-found parameters to a scientifically designed mineral sampling program, be it by drilling or other means. FACTORS IN SAMPLING DESIGN It was shown in Chapter 8 that three major factors should be considered in any mineral

Jan 1, 1980

By K. V. S. Sastry, M. Cross

A summary of recent progress in understanding the main factors affecting the pelletization of fine particles is presented. A scheme for categorizing the mechanisms responsible for pellet growth is out- lined and laboratory methods to both identify the important growth mechanisms and quantify the effects of the major factors influencing the rate of pelletization are described. Next laboratory and mathematical simulations of the commercial process involved in pelletizing iron ore concentrates, are presented. The operational instabilities associated with this pelletization process are described and subjected to a control theory analysis. This analysis, in conjunction with the mathematical models, is used to both explain existing control problems and assess the effectiveness of possible circuit redesigns at producing a more stable and controllable operation. Although much of the discussion is in the context of iron ore pelletizing the approach developed to analyze the agglomeration behavior of these concentrates should apply to most other fine particle systems.

Jan 1, 1980

By T. Airaksinen, R. T. Hukki

A new static pneumatic classifier for the primary separation of the feed material for microclassification is discussed. Pilot plant test results and a novel flowsheet for microclassification at the industrial scale are presented.

Jan 1, 1980

By W. E. Anderson, T. M. Brady

As part of a larger study to identify factors influencing the practical operating life of wire rope used on large draglines in surface coal mining, field trips to operating surface coal mines were made during late 1975. Wire rope performance information was obtained from personnel at 13 mine sites west of the Appalachians. Seventeen pieces of equipment, utilizing bucket sizes ranging from 30 to 220 cu yd (23 to 168 m), were documented. Draglines at large US surface coal mines can be represented as 120 machines having 60-cu yd (46-m3) buckets, moving 1.8 X 109 cu yd (1.4 x 109 m3) of overburden during 6650 hours of productive availability per year. Based on the limited field study, the calculated downtime resulting from rope-related causes averages 105.6 hours per year for each typical 60-cu yd (43-m3) dragline. The total loss in production from this source alone is thereby estimated at about 25 x 106 cu yd (19 x 106 m3) annually. Although study findings did not reveal anything about dragline rope life that wasn&apos;t known or practiced by one operator or another, most operators can expect improved rope life by periodic review of their practices and by adopting one or more life-improvement measures employed at other sites. Since rope productivity was found to vary by a factor of five among the sites studied, considerable improved average performance is possible. As little as 10% overall improvement would increase national productivity by 2 million cu yd (1.5 X 106 m3) of solid overburden removal. Associated savings in rope costs would be some $2 million annually, plus a large reduction of labor-related expenses. This report outlines preliminary findings which may prove useful to many operators in extending wire rope life. Some of these modifications or adjustments in maintenance/operating practices would not require capital investment. During the field survey, no company was found which had tried cost reductions by using presocketed dump ropes, or dump rope sheaves that opened like a snatch block, so these are suggested as possible improvements requiring modest capital input. Data Acquisition During the field visits, mine operators provided rope life information about their machines. Some of the rope life data consisted of gross averages; other data was in the form of detailed records, including rope construction and manufacturer, cutoff and resocketing periods, end-for-end switching, and downtime for rope change-out. Trends of average hoist rope life and average drag rope life determined from the field study are shown in [Fig. 1] as a function of bucket size. The three lines on the graph have slopes of 1, M, and 1/4. A comparison of the data shows that hoist ropes moved about twice as much material as drag ropes prior to retirement, although more than a two-to-one scatter within each category is evident. As expected, the larger machines with the larger buckets moved more total volume of material. The four pairs of solid symbols represent those data for which detailed rope life histories are presented in subsequent figures.

Jan 1, 1980

By Roy C. Kirkman

Dear Editor: It is with great pleasure that I read Mr. Howard M. Wells article in the December 1978 issue of MINING ENGINEERING entitled: "Optimization of Mining Engineering Design in Mineral Valuation." Mr. Wells very adequately presents the case and point that there are a great number of variables which must be analyzed during an economic evaluation of an FUND RESOURCE, such as copper or uranium. I wish to take this opportunity to suggest that, given today&apos;s economic climate, decision making takes place under conditions of uncertainty and that this uncertainty justifies our need to examine each one of the parameters entered into the evaluation model. It is my contention that the influence of the tonnages and grades as well as their distributions, have the most profound effect upon the results of an evaluation. Everyone concerned with the evaluation of FUND RESOURCES realizes that as metal prices decline or stagnate with sharply rising direct operating costs, cutoff grades (Gc) must increase according to the equation below which Mr. Wells uses: Gc = Total Operating Cost/(Market Price X 20 X Recovery) However, historically, we have seen cutoffs move dramatically lower in both the copper and uranium industries for the past decade. Henceforth, this established the metals industry most important argument for processing greater tonnages of lower grade materials from disseminated deposits (refer to paper by Kirkman, Roy C.). These disseminated deposits, created by either concentration processes (uranium) or dispersion processes (copper, gold, molybdenum), have log-normal grade distributions (Fig 1). Gross profits are rising, but unit profits are falling. The industry has created longevity through economy of scale, i.e., mining vast tonnages of low grade. In order to develop the great tonnages necessary to prove economic viability, we must examine alternatives at the low-end of the tonnage grade relationship. Notice from [Fig. 2] that as we move further to the right away from line A-B drawn tangential to the average grade curve at 45°, total profits will increase (given fixed annual production capacity) and unit profits decrease. The theoretical optimum operating point is where: [ ] At this point my observation is that slight shifts in production capacity bring about greater changes in profitability due to greater grade changes. Therefore, the best financial risk evaluation is obtained by totally revising the mining engineers methods and fixing the financial parameters such as discount and interest rates. A 10% shift in either of these two parameters will not cause near the same variance in economic viability as will a change on the GRADE-TONNAGE curve [(Fig. 2)].

Jan 1, 1980

By Kim C. Harden

INTRODUCTION The purpose of the following discussion is to present the state of the art of solution mining. Since the economics of a mining method ultimately determines its applicability and viability this presentation shall revolve around the costs of in- situ solution mining. First the assumed physical characteristics of the hypothetical ore body are described, followed by the appropriate operating assumptions. Then after a brief discussion on the type of surface plant to be used, the assumed project time tables and costs for Texas and Wyoming are presented. Finally, the economics of in-situ uranium leaching are analyzed through the use of discounted cash flow rate of return analysis. ORE BODY CHARACTERISTICS The assumption of the ore body characteristics is probably the most variable portion of this discussion. The characteristics that have been used are based mainly on state of the art technology, however, consideration of the most common depths of ore, ore thicknesses, and permeabilities also influenced these assumptions. In addition, it is assumed that these assumptions are equally applicable to Texas and Wyoming. The average grade of the ore is assumed to be .09% U308 with no apparent disequilibrium. The average thickness of ore is 2.29 m (7.5 ft) which results in an average grade-thickness (GT) of .675. The assumed depth to the top of the ore is 121.92 m (400 ft), the ore density is placed at 1.78 gm/cc (18 cu ft/ton), the porosity is estimated to be 28% and the permeability 1 darcy. These assumed ore body characteristics are shown in Table I. In addition, it is specified that the costs to be later discussed are based on a minimum GT cut-off of 0.15. It is more common to use GT cut-offs of 0.30 to 0.50 but GT cut-offs as low as 0.15 in conjunction with a minimum grade of 0.05% U308 have been used in the past with success and is considered state of the art. The ultimate percentage of uranium recovered from the ore is left to the discretion of the reader since the costs and economics are based on pounds recovered by the surface plant. OPERATING AS.SUMPTIONS An annual production rate of 200,000 lbs U308!yr was chosen for this example. In order to maintain this production rate, based on the ore body characterized above, a flow of 4731 liter/min (1250 GPM) with a recovery solution grade averaging .039 gm U308/liter is assumed. A regular 5 spot well field pattern is used with a well spacing of 21.5 m (70.7 ft) between like wells and 15.24 m (50 ft) between unlike wells. This well spacing gives each well an area of influence equal to 232.25 sq m (2500 sq ftl. An excess wells factor of 1.17 is used to estimate additional monitor wells and well field boundary wells. Each production well is expected to yield an average flow rate of 37.85 liter/min (10 GPM). In addition it is assumed that the ore body has a good shape in that it is not tenuous and narrow but has at least an average width of 200 ft. The process chemistry required for this ore body is assumed to be based on the sodium carbonate System- Oxygen is the chosen oxidant. Sodium chloride elution followed by precipitation with hydrogen peroxide makes up the remaining portion of the process. A fluidized up-flow ion exchange system is specified. The operating assumptions are listed in Table II. Restoration of the ore body shall be assumed to be accomplished through the use of ground water flush. Other methods may be considered as having to fall within the costs estimated for a ground water flush in order to be economic. In Texas it is assumed that a high capacity disposal well (200 GPM +I is required and in Wyoming evaporation ponds covering approximately 35 acres are to be used. No specific cost has been given to restoration. Instead only the additional capital investment for restoration equipment is given. Then, one year of restoration operating expense is estimated and included as the operating expense for one year beyond the last pound of U308 produced. It is also assumed that restoration will be pursued in the mined out areas of the ore body contiguous with ongoing production.

Jan 1, 1980

By E. G. Davis, G. V. Sullivan, J. P. Hansen

As part of its overall goal to maintain an adequate supply of minerals to meet national economic and strategic needs, the Bureau of Mines, U.S. Department of the Interior, investigated the feasibility of producing subsieve-size material by an attrition grinding method. The Bureau-patented technique employed intense agitation of a mixture of the material to be ground, a granular grinding media, and a suspending fluid. A variety of materials were successfully ground to extremely fine particle sizes. Studies were made to determine the method&apos;s efficiency in grinding industrial minerals and metals to minus 2 micrometers and ceramic powders to an average particle size of 500 angstroms. Transfer of this technology to a commercial scale has been achieved. Commercial-scale units are currently being used in the paper-coating clay and titania pigment industries.

Jan 1, 1980