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By C. P. Moore, G. W. Taylor

Vertically dipping lenses of nickel-copper ore at Dumbarton Mines Limited are being mined by a modified blasthole stoping method. The principal access to the mine is provided by a 15-degree decline, which, in conjunction with the use of ramps and declines for secondary access, maximizes the accessibility and mobility of trackless mining equipment. Sublevels are driven in ore on 80-foot vertical intervals and subsequently the ore, ranging in thickness from 15 to 30 feet, is slashed to its limits by a procedure of face sampling and test holing. Two longhole drill jumbos are used to drill off 40-foot vertical slices above and below these levels. Following blasting, the ore falls by gravity to the 500-foot horizon, where it is removed from drawpoints by load-haul-dump units and transported by truck to the main orepass. The rock is crushed to minus 3-4 inches and conveyed to surface by a 30-inch-wide wire rope suspended conveyor. This is achieved in two flights, a lower one of 290 feet and a main flight of 2260 feet. All aspects of the mining operation are discussed in the paper, including ventilation, services and safety.

Jan 1, 1973

By Harsh Deep Chopra, Jason N. Armstrong, Susan Z. Hua

"Existence of anisotropic Curie temperature materials [E. R. Callen, Phys. Rev. 124, 1373 (1961); J. Appl. Phys. 32 S221 (1961)] is a longstanding prediction - materials that become paramagnetic at a lower temperature along certain crystal directions while remaining magnetically ordered in other directions up to a higher temperature. Validating Callen's theory, we show that all directions within the basal plane of monoclinic F e1Ss (pyrrhotite) single crystal remain ordered up to 603 K while the c-axis becomes paramagnetic at 225 K. Results prompt a re-evaluation of existing magnetic materials with a focus on magnetic characteristics along different crystal orientations above instead of below the ordering temperatures. Theoretical guidelines for identifying new materials with large anisotropy of Curie temperature are also given, and analysis protocol to characterize them in a self-consistent manner is discussed. Materials with such a large directional dependence of Curie temperature open the possibility for uniquely new devices and phenomena, including energy storage and spintronics devices.IntroductionThis paper is an overview of our recently published work on anisotropic Curie temperature materials [l]. As a background, ferromagnetic and ferrimagnetic materials are characterized by a critical temperature below which magnetic interactions prevail over thermal agitation, leading to the appearance of a spontaneous magnetization. Above this critical point, called the Curie temperature, thermal energy eventually overcomes magnetic interactions and the material becomes paramagnetic.It is less well known that the Curie temperature varies with the orientation of the crystal. In ordinary ferromagnets this orientation dependence of Curie temperature is negligible because of the vanishingly small ratio of anisotropy to exchange energy, i.e., the spherical or isotropic exchange term dominates. Thus Curie temperature in ordinary ferromagnets appears to be an isotropic property, and assigning it a single characteristic ordering temperature suffices. However, a 'small' difference is not equivalent to being the 'same', and under appropriate set of conditions the anisotropy of Curie temperature is predicted to become appreciable, as discussed in the following.In formulating the theory of 'anisotropic magnetization' [2, 3] E. R. Callen and H. B. Callen first discussed the ""interesting possibility"" of anisotropic Curie temperature [2] or ACT; Callen and Callen noted that it was W. J. Carr, Jr. who initially raised this question, and they discussed it in detail at the Conference on Magnetism and Magnetic Materials (NY, November 1960), see footnote on page 320 of Ref. [2]. Soon thereafter, E. R. Callen developed the theory underlying the anisotropy of Curie temperature and conditions conducive to its observation [4, 5]."

Jan 1, 2013

By A. A. Paoli

The selection of a mining plant for carrying on development work presents many problems distinct in themselves, and affected by various local factors. In this paper, the writer proposes outlining and discussing in some detail the chief factors governing the economic selection of such plants. This will be followed by an enumeration of the underground and surface plant required for carrying on several hypothetical exploratory and mining operations. Where it is impossible or not convenient to obtain hydro-electric power, and where wood for fuel is scarce, we now find oil engines being used. A 100 h.p. oil engine, such as would be required to operate a three-drill air compressor, consumes approximately five Imperial gallons of fuel-oil per hour at full load. On the basis of a 60 per cent load factor, this gives, for eight hours' operation, a probable actual consumption of twenty-four Imperial gallons.

Jan 1, 1929

By A. E. Boone

"The paper presents critical areas in which improved coordination of effort by industry, government and sup-pliers will be essential to continue the growth record of the Canadian mining industry into the 'seventies'. The analysis includes: exploration, production, mining methods, research and development, markets, management and industrial relations. Performance objectives are suggested where tangible results can be measured. The author suggests the methods by which the 'seventies' can be the greatest decade in the history of Canadian mining. It is indicated that a national mineral policy is essential to the Canadian mineral industry."

Jan 1, 1970

By D. T. Pritchard

"Introduction""No accounting system is very good, and all of them are infinitely variable*.”The purpose of this chapter is to discuss those facets of a typical accounting system which are most commonly encountered by operating managers in mineral processing plants. However, before concentrating in any detail on these it is important to understand the broad purposes and basic techniques of any accounting system in any major business.The three broad purposes of an Accounting System are:- Administering, controlling, and recording the flow of cash in and out of the business. Cash is, of course, converted into other assets (or stores of value) such as inventory, plant and equipment, etc. These assets also have to be administered, controlled and recorded.- Internal reporting to Management for information, for control, and for use in making business plans and decisions. - External reporting to stockholders, government, lenders and other outside parties.In this chapter we shall organize our discussion of accounting practice in mineral processing plants around these three purposes of accounting and focus in some detail on specific practices and techniques with which operating personnel will be routinely involved. This chapter is divided into the following: Accounting Basics; Administration, Control and Recording of Cash Flows; Internal Reporting; Planning and Budgeting; Cost Control; and External Reporting."

Jan 1, 1989

By L. M. Nuelle

Rare earth element (REE)-and gold-bearing breccia pipes are a potentially significant economic target in the Pea Ridge iron ore mine, Washington County, Missouri. The Pea Ridge deposit is one of eight known volcanic-hosted iron ore deposits in the Middle Proterozoic St. Francois terrane, which are similar to the Olympic Dam-type deposits of Australia. The iron orebody is steeply dipping, tabular-shaped, and cuts across the host rhyolite. The footwall of the deposit is zoned from the massive apatite-bearing magnetite core outward to heterolithic breccia, pseudobreccia, specular hematite zone, to an extensive silicified zone. The hanging wall is zoned from the massive magnetite core outward to a heterolithic breccia, pseudobreccia, and an amphibole skarn zone. The REE-rich breccia pipes cut through the various lithologies along the footwall at or near contacts. They are typically 60 m long, 15 m wide, and extend at least 120 m vertically. The pipes are comprised of fragments of rhyolite host rock, massive magnetite zone, specular hematite zone, and silicified zone rocks supported in a matrix of rock flour, barite, feldspar, monazite, apatite, chlorite, xenotime, and, locally, gold. Total REE oxide content of samples of the ground mass material, which are not diluted with lithic fragments, average about 20 weight percent. Grades from working faces in the mine are lower and average about 12 weight percent. Gold distribution is erratic, but concentrations are as high as 371 parts per million.

Jan 1, 1991

By B L. Dickson, E, M F. Lee, P A. Mikula

Computational techniques are needed to assist in the analysis and interpretation of the increasing amounts of geoscientific and mining related data and information that are routinely gathered at mine sites. New interpretation methods are needed to provide an integrated approach so as to establish relationships (cause and effect) or to be predictive about possible outcomes based on acquired data. Traditional multivariate statistical methods are often confused by variable relationships that are non-linear, data distributions that are non-normal, and by the data themselves that may contain missing values, text and both continuous and discontinuous numeric values. Modern data mining methods are available to understand the relationships within and between diverse data sets, and identify relationships or trends associated with processes, measurements and mine design parameters in mines. The self-organizing map (SOM) is a data mining approach with the advantage that all input data samples are represented as vectors in a data-space defined by the observations (variables). The SOM procedure is an exploratory analysis tool that highlights patterns and relationships. Results are internally derived, in an unsupervised fashion based on measures of vector similarity. Our SOM outputs are highly visual, which assists in understanding and illustrating the dataÆs structure and internal relationships. Two studies are presented. The first uses SOM to investigate the relationships between a range of measured and derived rock property parameters and their observed behaviours during mining. Our aim was to determine whether a SOM analysis would allow a better understanding of observed and predicted rock behaviours from their rock properties. The SOM analysis showed that there were indeed relationships between æbrittleÆ, æsugaryÆ, æslabbyÆ and æsqueezingÆ rock behaviours and a number of the input parameters. The computed SOM æstructureÆ was then used to assess the likely behaviour of unknown samples by assigning them into behavioural fields based on their measured and derived geotechnical responses. The second study was aimed at assessing whether a SOM analysis of microseismic data at the Kalgoorlie Consolidated Gold MineÆs (KCGM) Mt Charlotte mine can contribute towards understanding and potentially forecasting/minimising seismicity at the mine-design stage. The database comprised 40 sample æclustersÆ of microseismic parameters from the MS-RAP software package, which were derived from 2500 individual seismic events. The SOM analysis showed that some of the initial mining conditions are related to the seismic parameters. In each of the studies, the SOM procedures assisted in understanding the data and provided new insights. Because of its æordered vector quantisationÆ foundation, the SOM procedure is a substantial improvement over traditional statistical methods in three main areas:its ability to analyse data from disparate sources, including different data types; its ability to analyse sparse data sets with missing values; and its ability to analyse and visualise non-linear relationships within a data set.

Jan 1, 2006

By Kevin Kuhl

With the destruction of the US-90 Bridge spanning St. Louis Bay by Hurricane Katrina, the State of Mississippi awarded its first major design-build contract in order to have a completed four-lane bridge in a period of less than two years. The structure consists of 76 pre-cast concrete beam spans with a total bridge length from Bent 1 to Bent 77 of 11,124 ft (2.1 miles). All 77 bents are founded on pre-cast, pre-stressed concrete piles and consist of two foundation types: pile bents and water line footings. A total of 53 pile bents were utilized where the deck is less than 52 ft above the water. Further divided, 10 pile bents, supported by 24 in. square, solid piles, are located on land. The remainder of the pile bents are located within St. Louis Bay and supported by 36 in. square, voided piles. All the waterline footings are supported by 30 in. square, voided piles. In total, 138 -24 in., 437 -30 in., and 463 -36 in. piles support the structure. Production pile design was based upon information gathered from the subsurface investigation, design soil profile and 23 out-of-position test piles. Verification of the design was established by monitoring the first production pile driven at each bent using the Pile Driving Analyzer. Particular challenges included highly variable coastal deposits, loads in excess of 1600 kips per pile and a compressed construction schedule. Initial drive capacity of a portion of the production test piles was less than expected resulting in a minimum 14 day setup. Following the setup period, restrikes were necessary to verify capacity. Project production piles ranging from 50 ft in length to in excess of 160 ft in length were used to achieve the required resistance. This paper includes a brief overview of the foundation design and indicator test pile program. The main objective is to provide a summary of the quality control procedures including establishing the driving criteria for each bent and to present issues that arose during production pile driving and the solutions that followed.

May 11, 2007

By V. Bazhko, V. Yahorava

The calcium sulphate waste stream of the wet phosphoric acid process, commonly called phosphogypsum (PG), contains the majority of rare earth elements (REE) initially present in the apatite feedstock. Mainly light and middle REE are present in PG and their total concentration ranges from 0.27% to 0.35% by mass. Worldwide, around 7 billion tonnes of PG have been produced to date at a current growth rate of 150-200 million tonnes per annum. In total, an estimated 21 million tonnes of REE are locked in PG waste dumps around the world. Due to the value of the REE contained in PG dumps a number of processes have been devised for their recovery. The majority of these processes applied complete or partial gypsum dissolution, but were deemed not viable due to high capital and operating costs. Mintek developed an alternative method for the recovery of REE from PG by applying Resin-in-Leach (RIL) technology. This technology was tested on PG sampled from dumps and current arisings from South African phosphoric acid production plants. The extensive testwork program included evaluation of various lixiviants and optimisation of lixiviant additions, optimisation of REE leach and adsorption conditions, batch equilibrium and kinetic adsorption tests, continuous RIL testwork and numerous variability tests. It was found that PG from different sources was highly variable, both in terms of REE recovery as well as physical properties of the material such as viscosity and filterability of the slurry. The recovery of REE varied from 15% to 80% depending on the origin of the samples. A high-level economic study indicated that at a price of >21 $/kg for mixed REE oxide product in conjunction with an overall REE recovery as low as 15% the economics of REE recovery from PG via RIL technology may already be favourable.

Jan 1, 2016

By Lauri Holappa

Copper converting is mostly performed in Peirce-Smith converters. The process is still very similar to the original one developed in the early 20th century. It is a batch process in a horizontal cylindrical reactor with air blowing via tuyeres along the length of the reactor side. The Peirce-Smith converter has its roots in Bessemer's inventions in the 1850's as he tested both horizontal and vertical vessels for steel converting. However, for steel making a vertical pear-shaped converter with air bottom-blowing was established. In the course of time, there was a distinct necessity for oxygen usage instead of air due to harmful effects of nitrogen to steel properties and its cooling effect. In-bath blowing of oxygen did not succeed, however, and top-blown oxygen converter with oxygen lance (LD or BOF) was first developed in he 1950's and emerged rapidly to a dominating position. Somewhat later oxygen bottom-blowing via special shrouded tuyeres was developed (OBM or Q-BOP) but has attained only fractional share. Bottom-blowing technique had, however, impact on the current combined blown converters which adopted the benefits of both top and bottom blowing. In copper converting Peirce-Smith type converters have kept their position until today although new processes have been introduced and at least few of them seem to be emerging. In one respect copper converting has a clear leading position i.e. in the progress of continuous converting processes (Mitsubishi, Ausmelt). These processes utilise top-blowing lances instead of in-bath blowing tuyeres. A different principle for continuous converting is flash converting by Kennecott Outokumpu, which makes smelting and converting independent of each others. Solid ground matte is used as a feed for flash converting in a reactor shaft similar to Outokumpu matte flash smelting. A comparable process has been presented by Inco too. The paper discusses principal physico-chemical and process technical similarities and differences in copper and steel converting. Although these processes are metallurgically quite different it seems that during the modem history of ferrous and non-ferrous metallurgy, starting from the 1850's, the exchange of knowledge between these disciplines has been quite intensive. In long-term perspective, many similarities in the development can be found but also divergences due to different ambient circumstances.

Jan 1, 2003

By H Esterhuizen

The Ernest Henry Mine (EHM) in Queensland, Australia is a Sub-level Caving operation that started production below the previously mined open pit at a depth of 535m. Current Production mining has progressed to a depth of 730m, with planned production mining to extend down to at least 1000m below surface. The inclined nature and geometry of the orebody combined with geological structures provides for challenging mining conditions. Over several years, Ernest Henry Mine has introduced measures to improve outcomes based on observations, monitoring and data analysis. As mining progresses deeper, EHM will continue to proactively take steps to ensure future outcomes are anticipated and mining can continue safely and uninterrupted. The focus of this paper is on the changes in seismic- and stress-driven behaviour of the rockmass experienced at EHM, the ground control measures implemented, and the anticipated future conditions and controls required. CITATION:Esterhuizen, H, 2018. The evolution of seismicity and ground control measures at Ernest Henry Mine, in Proceedings The Fourth Australasian Ground Control in Mining Conference (AusRock), pp 20–41 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 30, 2018

By M K. Kapo, S C. Nzama

The success of a mining operation depends on the quality of data used in decision-making processes and the people involved in making operational decisions. At Olympic Dam, mine geologists form an integral part of the teams that make decisions at various key points in the mine operational value chain. Mine geologists are directly and indirectly involved in all stages of the mining process, namely, orebody definition and categorisation, mine design and planning, metallurgical processing, and reconciliation.Due to the sheer size and complexity of the Olympic Dam deposit, each mining stage has been divided into smaller units within which decisions are made in line with the overall mine operational plan. In each of these units, the decisions and inputs made by mine geologists has ensured that consideration of geological factors is made in the mining process. Over time, the mine geology team has demonstrated a systematic approach in the development and improvement of their processes in line with the mine’s operational needs, such as understanding the in-stope ore variability and maintaining a consistent ore feed to the plant. An understanding and interpretation of the mineralisation distribution, based on acquired data, has proven to be important in the definition of resource modelling parameters. These parameters in turn affect the quality of grade estimates and their downstream use in planning, production and subsequent reconciliation processes. The continual study of the geology of the deposit, and unravelling its complexity through research has been crucial to the metals extraction process. The involvement of mine geologists through each of the mine value processes places Olympic Dam in a favourable position to benefit from future opportunities that will take advantage of the increasing operational demands and production pressures, and the ever changing economic conditions.This paper reviews the role mine geologists play in the realisation of the Olympic Dam deposit, from ore to product, through their interaction and collaboration with other departments and stakeholders. This paper also highlights mining practices employed at the Olympic Dam mine.CITATION:Nzama, S C and Kapo, M K, 2014. Managing the giant – a mine geologist’s perspective to the mining of the Olympic Dam deposit, in Proceedings Ninth International Mining Geology Conference 2014 , pp 451–460 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 18, 2014

By J. F. T. Agapito

The load carrying capacity of oil shale pillars excavated by conventional blasting, presplit blasting, and mechanical mining is evaluated. The study was based on a comparison of in-situ vertical stresses and fractures obtained from overcoring horizontal holes in the Colony Mine, Piceance Creek Basin, Colorado. Results indicate that conventional blasting causes a zone of damage approximately 3 m (10 ft) thick with low stress distributions. Presplit blasting reduces damage significantly, and increases the load carrying capacity in the 3 m (10 ft) thick zone by 5.93 MPa (860 psi). Mechanical mining causes little or no rock damage, and an increase of 9.83 MPa (1425 psi) in strength in the same 3 m (10 ft) thick zone. An example of pillar design is given showing that the use of presplit blasting and mechanical mining techniques can increase the extraction ratio by at least three and five percent, respectively, as compared to conventional blasting. It is speculated that comparable increases in extraction should also occur due to increases in span dimensions.

Jan 1, 1984

By Aaron Jones, Guy Reed, Russell Frith

"In 2017, one of the international authorities on coal bursts, Dr. Chris Mark, published a paper entitled “Coal Bursts that Occur during Development: A Rock Mechanics Enigma,” in which several relevant technical issues were identified, the most pertinent being:i.whilst development coal bursts are commonly associated with geological faults, understanding which specific faults result in burst-prone development mining conditions and why, remains undefined.ii.conventional wisdom in relation to strong roof and floor geology of the coal seam might be limiting, based on certain burst examples in Colorado.iii. development coal bursts can occur without the local ground stresses being substantially elevated from their in situ levels.This paper outlines what is considered to be a credible, first-principles, mechanistic explanation for these three current development coal burst conundrums by reference to early published coal testing work examining the significance of a lack of “constraint” to coal stability and an understanding of how very specific structural geology and other geological features can logically cause this to occur in situ, albeit on a statistically very rare basis. This basic model is examined by reference to published information pertaining to the development coal-burst that occurred at the Austar Coal Mine in New South Wales, Australia, in 2014 and from the Sunnyside District in Utah, USA.The “cause and effect” model for development coal bursts presented also offers a meaningful explanation for the statistical improbability for what are nonetheless potentially highly-destructive events, being able to explain the statistical rarity being just as important to the credibility of the model as explaining the local conditions associated with burst events.The model could also form the basis for a robust, risk-based approach utilising a “hierarchy of controls” to the operational management of the development coal burst threat. Specifically, these include the use of pre-mining predictions for likely burst-prone and non-burst-prone areas, the use of the mine layout to avoid or at least minimise mining within burst-prone areas if appropriate, and finally the development of an operational Trigger Action Response Plan that reduces the likelihood of inadvertent roadway development into a burst-prone area without suitable safety controls already being in place."

Jan 1, 2019

By R. B. Sudderth, A. Quiroz G., M. Torres M., C. Salgado Q., J. Fernández O., H. Bravo P., M. Torres B.

SNF FloMin, Inc. has introduced a complete line of extractants for recovery of various metals. Among them are the CuPRO MEX™ Brand of copper extractants that are based on the well- known 2- hydroxy 5-nonylsalicylaldoxime and 2-hydroxy acetophenoneoxime. This paper presents the laboratory and pilot plant trial results for SNF FloMin’s CuPRO MEX™ 3302 reagent, the equivalent to the wellknown ACORGA® M5640 extractant, and the composition of these reagents are described. Some examples of SNF FloMin’s CuPRO-Sim™ Advanced solvent extraction simulator are presented.

Jan 1, 2014

By J. Ning, T. Bu, J-Q. Jiang, L. Jiang

"In coal mining in China, the cutting height of the shearer in longwall faces is increasing. Owing to the increase of extraction height, the caved roof strata area is enlarged, and new issues are being encountered, such as determination of a suitable working resistance for the shield and control of the roof. Through field observation and theoretical analysis of the first longwall face with a height of 6.0 m in the Bayangaole mine, a three-stage structural model was developed. Stage I is defined as the period in which the lower immediate roof (LIR) caves into the goaf and is broken into irregular shapes of various sizes. Stage II is defined as the period in which the upper immediate roof (UIR) breaks and impacts the LIR. In stage III, the main roof breaks into blocks and then impacts the UIR. With respect to these three stages, a suitable method was identified for calculating the working resistance of the shield support for a super-great mining height longwall face (SGMHLW). Introduction and backgroundThe coal seams in the Shendong coalfield, located in the northwest of China, are characterized by low dips and large thicknesses and are thus suited for full thickness extraction. Since the mid-1990s, the Shendong coalfield has been developed into one of the largest in the world (Ning, Liu, and Tan. 2014; Ning et al., 2017). Recent developments in mining equipment have made it possible extract entire seams up to 5.0 m thick in a single cut. This method, termed the ‘super-great mining height longwall face’ (SGMHLW) method, has been widely adopted in the Shendong coalfield (Table I) (Ju and Xu, 2013; Peng, Li, and Zhou 2015; Zhang, Fan, and Ma 2011). According to some studies, sudden support-closure incidents often occur when using the SGMHLW method. The key to solving this engineering issue is to have a clear understanding of the structural characteristics and movement laws of the overlying strata. For instance, the load on the supports is related to the movement of the roof stratum as a response to the mining activities."

Nov 1, 2018

By William C. Smith

Roof support, an important aspect of ground control, involves maintaining roof competency to ensure a safe and efficient mining environment. Wide variability in rock quality and stress distributions requires a systematic approach to roof support design that satisfies specific goals. The success of past roof sup-port in reducing the incidence of roof falls has been primarily attributed to safer roof bolting practices. However, roof falls continue to be the number one occupational hazard in underground coal mines. This U.S. Bureau of Mines report presents a general overview of roof bolting and other roof support methods used in the United States. Characteristics of bad roof and associated roof failure theories are briefly presented as background to roof support. Methods of detecting and monitoring roof behavior and/or bolt performance provide essential feedback on roof support requirements. A discussion follows on roof bolt design that assimilates roof and support parameters into useful equations or nomographs to help decide what bolt types to use and how they should be installed under different roof conditions.

Jan 1, 1993

By S. F. Emmons

Jan 1, 1899

By T. Lamb

There are many honor stories about aluminum in the marine environment and many are not based on facts, so they are myths. Myths must be addressed before progress can be made. This paper attempts to dispel the myths and state the facts. A common perception is that aluminum ships cost significantly more than steel ships. This paper illustrates that even though the cost of the aluminum structure is over 50% more than the steel structure, an "equivalent" aluminum naval ship can be built within 7% of the acquisition price of a steel ship. This is possible because of the cascading benefits of the aluminum ship's significantly lighter weight. Aluminum ships also have a life-cycle cost advantage over steel ships because of reduced maintenance and fuel cost savings.

Jan 1, 2011

By K. V. Godfrey

With the increasing need to exercise better control over mill circuits has come a requirement to develop rapid, accurate means of measuring circuit parameters. One of the most important parameters is the assay of the material in the circuit (or about to be introduced to the circuit). To date, most on-stream analysis has been performed using X-ray fluorescence equipment. Neutron activation offers an alternative method in certain circumstances, and one which has several interesting advantages. Recognizing the need for a simple, safe neutron activation unit suitable for on-stream analysis in the mineral industries, Atomic Energy of Canada Limited has designed, built and tested the SHERLOCK system. One prototype (SHERLOCK I) is located in Ottawa and is now used primarily in research. A second prototype (SHERLOCK III) is located in Vancouver at the laboratories of B.C. Research. This unit is being used for some development research and for evaluating the unit in specific applications. Most of the work completed to date has been aimed at proving the technique and in developing some of the parameters needed to design systems for a milling plant. Funding for the work has been through research grants and through sponsor¬ship by interested companies.

Jan 1, 1971