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By R Chinamatira

Several technical and economic factors have to be taken into consideration in developing an optimal mining method. This paper describes some of the important factors learnt during the evolution of the sublevel cave mining method at Trojan Nickel Mine, part of the Bindura Nickel Corporation (BNC) in Zimbabwe. Sublevel caving (SLC) has been successfully implemented at Trojan mine since its introduction in 1994. The method has evolved over the past six years into a system that has brought about improvements in efficiencies and productivity. Although the original design parameters used were sound and provided a solid foundation for the system, they needed to be optimised to get the best out of the mining method. Improvements and changes have been made in areas such as the drilling process, charging and blasting techniques, ring pattern design, development size and shape, and the draw control system. This has enabled the mine to develop an SLC operation that is efficient and innovative. Experience gained, together with the theory available has given us a much better understanding of the system. This knowledge will be used in the future to enhance the system further. Given the low grades of the BNC Mines, management recognises that only through technical excellence and efficient mining can the mines reduce mining costs and maintain profitability and competitiveness on the world market. In the Zimbabwe mining industry reaction to technological change, mechanisation and advancement have been relatively slow, due to isolation and economic constraints, compared to the rest of the world. Economic difficulties prevail, with high inflation levels, a poor exchange rate, lack of foreign currency and other associated problems. Despite these constraints, the bold steps taken have transformed Trojan mine into a more efficient and competitive operation, presenting itself as the leading mine in the BNC group. Appendices give data to illustrate the benefits obtained.

Jan 1, 2000

By S. S. Peng

To prevent mine floor heave, the mechanisms of floor heave must be fully understood. Based on the field study, the mechanisms of two types of floor heaves are analyzed in this paper. The mechanical models for the two types of floor heaves are developed. The floor heave can be predicted by the developed mechanical models and the control measures are recommended.

Jan 1, 1995

By J. Mothomogolo

Mining projects are capital-intensive and are also characterized by high technical and economic risks. These factors pose challenges to mining entrepreneurs when they seek to raise seed capital for mining start-ups. There are limited sources of mining investment funds in South Africa and each has shortcomings due to one reason or another. Another impediment is South Africa?s status as a developing economy, in which the standards of living ? which in turn influences the savings culture ? the limited GDPs and budget, the socio-political environment, and banking, mining, treasury and other regulations, determine the size of investments, particularly in mining ventures. The proposed funding mechanism was developed with the aim of filling the gaps identified in existing funding mechanisms that were developed by the government with the introduction of the Minerals and Petroleum Resources Development Act (MPRDA), 2002. The shortcomings identified were presented to the study participants as questions to obtain views that were used to define innovative ways of raising mining start-up capital. Most participants in the study supported the derived hypotheses and proposals, and these were used to refine the proposed mechanism for mining investment in South Africa. The proposed funding framework is aimed at encouraging interaction between mining entrepreneurs, government, and the investors to align goals and expectations when undertaking a mining investment.

Jan 1, 2012

By J. Worden, D. Hughes, S. Smart, H. Zughbi

The enterprise wide optimization (EWO) of steelmaking and manufacturing is a multi-level, hierarchical problem which spans higher level corporate planning and scheduling through to the lower level operations of processes that produce and manufacture steel. External and internal system dynamics combined with process unit co-ordination create complex changing circumstances for the enterprise. This paper presents a scoping study as a prelude to enterprise wide considerations at an integrated steelworks to help inform the choice of appropriate model types and optimization techniques. The hierarchical, multi-level structure of the enterprise and the important spatial-temporal scales to consider are defined. Insights into the system were gained by analyzing a large set of dynamic operational data. Over two years of data were subject to both univariate and multivariate analysis with the intent of understanding the complex interrelations of energy flows on site, the inherent system dynamics of the energy network, system operational modes, aspects of planning and scheduling and the coordination between major processing units. This analysis was further used to evaluate the performance of the system in regards to energy utilization and understand the potential economic benefits derived from improved operational decisions.

Jan 1, 2015

By Richard B. Diver, Mark D. Allendorf, Daniel E. Dedrick, James E. Miller, Roy E. Hogan, Andrea Ambrosini, Eric N. Coker, Anthony H. McDaniel, Nathan P. Siegel, Gary L. Kellogg

"Converting carbon dioxide and water to hydrocarbons is an attractive option for storing solar energy and, coupled with appropriate CO2 capture technology, for recycling carbon and impacting atmospheric CO2 concentrations. For any process, high solar-to-fuel efficiency is necessary for large scale viability and favorable economics. Thermochemical approaches for solar-to-fuel conversion are potentially highly efficient as they avoid the inherent limitations of photosynthesis and also sidestep the solar-to-electric conversion necessary to drive electrolytic reactions. Solar-driven two-step metal-oxide-based thermochemical cycles for producing the components of syngas, CO and H2, from CO2 and H2O are the basis of the “Sunshine to Petrol” project. Multi-cycle production of both H2 and CO has been demonstrated over several iron- and cerium-based compositions fabricated into monolithic pieces both in the laboratory and at the National Solar Thermal Test Facility. These compositions are being developed for deployment in a unique and continuous solar-driven reactor prototype, the counter-rotating-ring receiver reactor recuperator or CR5.IntroductionThe interconnected challenges posed by increasing global competition for petroleum and the increasing concentration of atmospheric carbon dioxide are now widely recognized. Meeting these challenges requires recognition that although hydrocarbon fuels are ideal energy carriers, they can no longer be thought of as primary energy sources. It is necessary to take the realistic view that our conventional fossil fuels are in fact “stored sunlight” in the form of “sequestered carbon.” This view leads to a search for options to use and store sunlight more directly.Sunshine to PetrolIn combusting hydrocarbons we unlock the energy for utilization, but we also release the carbon to the atmosphere. However, nature teaches us that with an appropriate persistent energy source, e.g. solar irradiation, it is possible to effectively reverse the combustion process and “reenergize” CO2 and H2O back into hydrocarbon form."

Jan 1, 2010

By Allan R. Punkkinen

Safe extraction of the valued ore resource in the deep levels of VALE Creighton Mine has progressed in a pillar-less fashion using vertical retreat, slot-slash and uppers retreat methods since the cessation of ?cut and fill? mining in the late 1980?s. Sequencing of the panel extraction and filling has been the key to successful exploitation of high stress orebodies at depth. In late 2010, discussions between the Operating Department and Creighton Ground Control revealed an opportunity to evaluate a trial primarysecondary sequence in the west end of the 400 Orebody at the 2340m horizon. To manage the trial primarysecondary project, a high level risk analysis and management of change was carried out to mitigate potential danger. As part of the requirements, an instrumentation project was conducted in the hanging wall and footwall bottomsills of the secondary panel and within the secondary panel itself. The extraction sequence was modeled with Map3D® software, confirming high stress levels with the advance of the primary panel. Enhanced ground support was installed based on modelling results. A key objective of the instrumentation project was to verify support system response to mining and to obtain knowledge in regards to the behavior of the stope. This paper describes the first time that this type of new innovative instrumented rockbolt technology had been used in a hard rock mining environment. Understanding of the physical deformation mechanisms of ground support in response to high stress conditions is the basis for an effective ground control strategy. The data played an important role in subsequent enhanced ground support system design at the mine and importantly, established the fact that the secondary pillar had not totally failed. Subsequent cavity monitor results helped establish that fact.

Jun 1, 2012

By S Love, M Anderson, M Boland

"The high rate of failure of new mine developments to meet feasibility study expectations has been the subject of many fine technical papers. Yet failure rates remain stubbornly high.Similarly, the common occurrence of disastrous acquisitions resulting from failed due diligence on projects is well known. Yet such mistakes continue to be made.The authors argue that project and due diligence failure are caused at least partly by cognitive biases. These biases pervade decision-making throughout project evaluations.A wider understanding of these biases (and their effects) is necessary. Only then can mitigating actions be taken.The opportunity for this wider understanding exists. A number of best-selling books have been published on the topic in recent years. With wider understanding of key concepts and terms, cognitive biases can be recognised and discussed. They can also be challenged and mitigated.The authors believe that these concepts should be entry-level, required knowledge for anyone evaluating, developing, reviewing or financing mining projects.Perhaps the most prevalent biases in project evaluation failure are the ‘over-optimism’ biases. In particular, the planning fallacy and confirmation bias.The anchoring effect is also pervasive. This bias propagates unrealistic assumptions from scoping and prefeasibility studies through to so-called definitive feasibility studies. Unrecognised anchoring biases also undermine the validity of many ‘independent’ due diligence reviews. They are also prevalent in corporate acquisitions.The availability heuristic refers to a mental shortcut that can lead to a number of biases. One of these is the narrative fallacy. The mind constructs coherent narratives and opinions, regardless of the amount and quality of the information that support them. Narrative fallacy commonly occurs in the evaluation of social and political risk. Another is disaster neglect, which is especially common in the failure to assess risks associated with tailings management.This paper outlines the relevance of these biases to mine project evaluations. It also provides examples where the authors have observed their effects.CITATION:Love, S, Boland, M and Anderson, M, 2016. Influence of cognitive biases on project evaluation, in Proceedings Project Evaluation 2016, pp 226–235 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 8, 2016

By William N. Poundstone

Since World War II, when off-track mining became popular, mining machinery has undergone much change. However, the change has been basically to make the machines more powerful, more productive and more reliable. Little change has been made, in this period, in the basic mining system. While steady improvement was made in productivity until the passage of the new Federal Coal Mine Health & Safety Act, I believe that the cost Co benefit ratio of further improvement from this basic approach of improving the existing extractive tool is not as promising as I believe may be obtained from a new approach. Consequently, six years ago Conoco and Consol undertook a comprehensive long-range R&D program to see if improvements of a more basic nature could be made in underground mining. We concluded early in our program that while many things currently limit the rate of production such as the rate at which roof can be supported, time needed to advance ventilation systems, time required to clean up and rock dust, time required to maintain and service equipment as well as time lost due to haulage deficiencies, that the key to improvement was a truly flexible continuous high capacity haulage. With face equipment in use today, mining rates can be increased with such a haulage system where the ability to support the roof exceeds the ability of conventional haulage equipment to remove the coal. More importantly, if we could develop such a system, it would set the stage for development of far more sophisticated methods of mining at the face than exist today, and as new and more dependable mining machines and methods are developed, continuous transportation will enable the gains envisaged in production to be realized.

Jan 1, 1974

By D Liu, M Edraki, L Berry

The presence of clay minerals slows down the settling rate and mitigates compact consolidation efficiency in tailings dewatering. The increasing use of saline water in many plants, affects the dewatering performance and presents the mining industry with new concerns. Efficient tailings dewatering is a great challenge due to the complexity character of tailings, especially clay mineralogy, clay content, and water chemistry. In this study, existing studies of the effect of different affecting parameters, such as pH, ionic strength and polymer flocculants, on clay aggregation behaviours are reviewed. The settling behaviours of three types of commonly observed clay minerals in tailings, kaolinite, bentonite, and illite, are also investigated in saline water with different water salinity as a case study. The settling rates of clay minerals are found to be affected by water salinity, clay type, clay content and polymer dosage levels. High salinity water hinders the settling of kaolinite but assists the settling of bentonite and illite through formation of different aggregation structures.The current work has indicated that strategies to promote more rapid dewatering could include adjusting flocculant type or level, water salinity and salt balance, and tailings solid content levels. Implementing dewatering strategies may require a more detailed knowledge of the effect of surface chemistry on the nature and strength of the clay inter-particle forces. This study discusses the research gaps on how to better manage clay-rich tailings in saline water and identifies new research directions. The development of a water management model, supported through in-line monitoring data to predict and manipulate of the surface chemistry of the clay component of the tailings could be a new direction to manage the issues associated with clay minerals in the process of dewatering and tailings management. Mine planning (water use requirements, operating costs) could benefit from more detailed studies on dewatering of clay-rich tailings in saline water. CITATION:Liu, D, Edraki, M and Berry, L, 2018. Improving the dewatering efficiency of clay-rich tailings in saline water, in Proceedings Mine Waste and Tailings Stewardship Conference 2018, pp 476–484 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 23, 2018

By J. J. Laffin

In the pursuit of comfort and safety, the wonders of science have given us controlled heating and cooling, thus enabling us to enjoy all the aspects of present-day living to an extreme never previously •envisaged. Man's attempt to conquer the elements largely involves con-trolling the temperature around him. Without having conquered this aspect, his body energy would be consumed in trying to maintain physical comfort, rather than being invested in the explorations which have resulted in man's control over the forces of nature. The indirect methods used to obtain the most agreeable temperature environment were developed because of the natural tendency to strive for increased safety, convenience and comfort. Until the twentieth century, when heat generated by atomic fission became a reality, man's only source of heat, except for that of the sun, came from his discovery of fire.

Jan 1, 1962

By P Audet, D R. Mulligan, D Doley

This analysis attempts to reconcile existing ecological theories, rehabilitation planning goals and implementation constraints in the form of a rehabilitation paradigm that considers potential and pragmatic ecosystem transformation pathways. The framework prioritises multiple developmental scenarios for post-disturbed landscapes within a continuum of ecological outcomes. A feature of the framework is that ænovelÆ ecosystems and agro-ecosystems, having a range of commercial and societal values, are valid outcomes spanning the conceptual divide between the ecological functions of under-rehabilitated versus re-instated ænaturalÆ landscapes, especially in a changing environment. Landscape suitability analyses are considered to be fundamental to the incorporation of regional landscape and climate in the implementation of land rehabilitation and management strategies. Altogether, the paradigm could facilitate the identification of widely pertinent rehabilitation goals having direct implications at the regional scale of restoration ecology and acceptance of the need for ongoing commitment to the management of disturbed environments.CITATION:Audet, P, Doley, D and Mulligan, D R, 2012. Can ænovelÆ ecosystems offer suitable rehabilitation alternatives for post-mined landscapes?, in Proceedings Life-of-Mine 2012 , pp 135-142 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 10, 2012

By T. P. Weldum, W. Conger

"These studies address the relationship between mill media sizing and its grinding efficiency. Starting with the results from a review of the literature, the issues of initial media sizing for a new ball milling circuit, and then optimal media sizing for an existing milling operation, were studied. The Functional Performance parameters “Mill Grinding Efficiency” and cumulative “Mill Grinding Rates” from both plant and test-scale equipment were used, and provide valuable new insight into this topic. A plant media sizing diagnostic tool is presented, as are newly developed testing equipment and evaluation methods, and recent case studies. REVIEW OF MEDIA SIZING LITERATURE For a plant metallurgist to answer the question “How can I maximize plant profit by manipulating this grinding circuit variable?” she must know what effect the variable has on grinding circuit efficiency. Despite the significant cost of grinding media and its potential effect on production capacity, the ‘best’ media sizing remains ill-defined for any given ball mill circuit in the industry today. The underlying reasons for this will be discussed. But the importance of this issue drove Metcom and its industrial partners to take on the challenge of how to engineer the ball charge for an existing grinding circuit. In the absence of any proven method, the first step was a review of the literature. Sponsored by Cleveland-Cliffs, Inc., a broad review of the literature was undertaken, producing “The Effect of Media Sizing on Ball Milling Efficiency” (McIvor, 1997). Among hundreds of publications that were reviewed that discuss the topics of media sizing or wear, forty-five were studied in detail. These were grouped into: plant experiences; laboratory and pilot plant investigations; media wear studies; population balance modeling studies; and general papers on ball milling which included the topic of media sizing. The reader is encouraged to refer to that review. The findings remain unchanged, although some relevant papers have been written since (e.g. Staples et al, 1997; Banasi et al, 1999; Orford et al, 2006; LaMarsh, 2015). The main findings of the review were as follows."

Jan 1, 2018

By D. D. Bell

This paper presents the history of uranium procurement and demand, and takes a look at future requirements. The three basic conclusions drawn are: (1) the productive capacity of former and existing producers whose operations may be profitably reactivated is insufficient to meet demand projected beyond 1975; (2) reserves in the $5 -$10 price range do not provide the flexibility to sustain production at the high rates required in the late 1970's; and (3) only higher prices can overcome these deficiencies, as this would provide sufficient inducement for the industry to explore for and develop new reserves and productive capacity.

Jan 1, 1967

By M. J. Beus

The U.S. Bureau of Mines is conducting investigations to improve design methods for mining volcano-genic massive-sulfide (VMS) type deposits in environmentally sensitive regions. This study was conducted at the Greens Creek Mine, which is typical of many VMS-type deposits throughout southeast Alaska, and served as a case history for computer modeling and structural analysis. Results indicated that the finite-element design method provided reasonable comparisons with both the anticipated regional stress regime and the measured deformational response of the underground accessways. Investigators concluded that reasonable accuracy can be expected for stability analyses of proposed mine design scenarios at this mine using the results of this preliminary study.

Jan 1, 2010

By Arka Jyoti Das, Prabhat Kumar Mandal

"Coal mining in India has a strategic importance for the energy security of the country. Presently, the majority of coal production is coming from open-cast mining. Due to the fast depletion of reserves amenable to open-cast mining, future coal production will depend primarily on underground production. In conventional bard-and-pillar/room and pillar mining as it is practiced in India, the percentage of extraction is very low. In fact, within most Indian coalfields, a large number of coal seams extract only 15- 20% of coal, but no pillar extraction is done due to the presence of surface or sub-surface structures leading to huge amount of coal being locked-up in underground. Spontaneous heating and fire, the accumulation of poisonous gases, severe stability issues, unsafe workings and environmental hazards are all major problems associated with these developed coal pillars, so there is a pressing need for technology in the mining industry to extract this huge amount of coal locked up under different constraints. In this study, we propose that the locked-up coal be extracted by replacing the developed coal pillars with artificial pillars. The paper briefly discusses the extraction methodology designed for this and its evaluation through numerical modeling for applied suitability underground.INTRODUCTIONDriven by rising populations and urbanization, an expanding economy and also a quest for improved quality of life, energy usage in India is expected to increase manifold in the coming years. As for India's energy scenario and its projected future plans, there is no doubt that coal will remain a prime source of energy, even over the next few decades.The majority of coal production in India comes from open-cast mining because of large-scale mechanization, but the coal reserves amenable to open-cast mining are gradually depleting - which may impose adverse impacts on the energy sector if underground production does not increase. Underground coal extraction, meanwhile, is going to become more complicated in near future due to the fast exhaustion of easily mineable coal reserves."

Jan 1, 2016

By B. F. Dickerson

STRATEGIC METALS! Recently, this money accented cry has been heard in such diverse locales as Mining company boardrooms, Banker's offices, Stockbroker's quarters, Swindler's dens and Congressional committee rooms. (In some cases, these locales are one and the same). Is the strategic metals rush for real? Should it be? Our paper attempts to give a very generalized view of the subject for a few metals, points to a few potential, but generally overlooked sources of these metals, and offers conclusions based on our studies.

Jan 1, 1981

By Lynn B. Hales

Unfortunately, the term "control" has a negative connotation in the minds of many of our operating plant personnel. Whereas the opposite is true of those associated with research and technical centers in our industry. The magnitude of this difference in opinion and actual experience has often proved to be a major factor influencing the success or failure of process control applications. Through the years, many plant people have endured a number of unsuccessful attempts by "outside" people to "optimize" their plants; and these experiences have proved to have had quite a callousing effect on them. On the other hand, in many plants, successful process control efforts have made firm allies of the operating personnel, and have increased the number of metallurgical people who are well qualified and experienced in process control. The instrumentation industry, computer industry, and the mining industry's ability to quantify what is really happening in our processes have grown and developed rapidly since the first control efforts were made in the 1930's (1). Because of this-,: new control opportunities are becoming increasingly more feasible and older well established ones are becoming even more practical and necessary with regard to the economic s of our industry.

Jan 1, 1979

By Nadir Ansari, Brian W. Wilson, Marina S. W. Li

"A hybrid shoring system consisting of cast-in-place soldier piles with Cutter Soil Mixing (CSM) infill panels was constructed for temporary support of a 19.8 m (65 ft) deep excavation in Vancouver, British Columbia, Canada. Deep Mixing (DM) was completed up to 9.7 m (32 ft) in fill, peat, wood waste and clayey silt with embedment in dense till, and soldier piles constructed through the dense till extending to below final excavation level. Two trial CSM panels were installed ahead of production to assist with developing the termination criteria of the CSM panels in the dense till. The constructed depth of the CSM panels was based on interpretation of real-time monitoring data obtained through the Bauer B-tronic system. Inclinometer monitoring data from two CSM panels and two soldier piles, as well as soldier pile survey target data was used to assess and monitor the performance of the hybrid shoring system throughout bulk excavation. The objectives of this paper are to provide an overview of the design and construction aspects of the hybrid DM shoring system and to present inclinometer and pile target data to demonstrate the lateral performance of the CSM infill panels and soldier piles. This paper also discusses the merits of using real-time monitoring data as part of the engineering decision-making process for validating CSM panel construction. BACKGROUND A hybrid DM shoring design was recently completed for a high-rise development in downtown Vancouver, British Columbia for temporary support of a five level basement excavation. Deep mixing was proposed by the excavation and shoring design-build team as the preferred method to construct infill panels between soldier piles because of the speed at which the shoring system could be constructed in variable fill, peat, wood waste and overburden compared with traditional secant piling methods. The development site is generally a truncated triangle in plan, with the longest side of the triangle being approximately 115.7 m (380 ft) long and the two shorter sides being approximately 71.6 m (235 ft) (Hybrid Shoring Wall 1) to 75.0 m (246 ft) (Hybrid Shoring Wall 2) long. The site is bounded by an existing bridge off-ramp structure along its longest side, and by city streets on the other two sides, as shown in Figure 1. The truncated section is approximately 16.8 m (55 ft) (Hybrid Shoring Wall 3) long. Due to project constraints, the hybrid DM and soldier pile shoring system was only proposed for the two shorter sides of the triangle and the truncated section. Traditional secant piles were installed for the longest side. This paper focusses on the hybrid shoring system. A typical detail showing the CSM infill panel with the soldier piles is presented in Figure 2."

Jan 1, 2017

By K Johnson, G Morrison, N Lisowiec

The Mount Wright gold deposit is located near the town of Ravenswood, ~90 km south of Townsville, in north Queensland. The deposit has been mined by underground methods since 2006. It produced approximately 138 koz Au in the 2011 - 2012 financial year and has a total endowment of approximately 1 Moz Au. To facilitate near mine exploration, a re-logging campaign of 600+ diamond and RC drill holes was recently conducted, resulting in a revised three-dimensional (3D) geological model and improved understanding of the ore controls and the mineralised system. The deposit is within a Permo-Carboniferous breccia complex approximately 350 m diameter and more than 1200 m deep. It consists of early peripheral granite-rich breccia, polymict breccia, a rhyolite spine and a late tuffisite (fine-grained milled breccia) pipe. The rhyolite spine is approximately 60 m + 250 m + at least 1200 m deep and is zoned with massive, flow-banded and breccia phases that are in part gradational with the other breccias. There is extensive sericitic alteration centred on the tuffisite and rhyolite units and fading out into the shallower and peripheral polymict and granite-rich breccias. There is also a broad pattern of metal zoning with elevated Pb-Zn ¦ Ag in the upper 400 m, Au-Cu-Bi below 400 m fading out below ~850 m, and a poorly defined deep Mo-W-Te-Sb anomaly. The majority of the Au ore is between 400 and 850 m below the surface in the rhyolite spine. Below this, Au mineralisation is less coherent, and more localised in the margins of the rhyolite and in the adjacent tuffisite. The developing model is that the ore is not confined to or necessarily directly genetically related to the rhyolite spine, but is driven by other phases of intrusion that also generated the tuffisite pipe. This model is being used to generate additional drill targets away from the present mine development.CITATION:Johnson, K, Morrison, G and Lisowiec, N, 2013. Advancing near-mine exploration with an updated geological model for the Mount Wright gold deposit, Queensland, in Proceedings World Gold 2013 , pp 469-478 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 26, 2013

By J. Scrimgeour

"The word ""instrumentation"" has expanded from its original meaning, which in engineering perhaps referred to measuring apparatus alone. In its broadest form, it now includes sensors, display instrumentation, standard pack-aged controllers and, most recently, the use of stored program computers for on-line process control. The paper traces the evolution, in tutorial form, of the successive application of mechanization, measurement instrumentation, automatic control, central operating systems, programmed control, process computer control, direct digital control and, finally, hierarchies of computers used for process control and corporate management as a fully integrated business system. In the field of industrial minerals, the cement industry has seen the most widespread acceptance of these techniques. Computer control has been accepted as the way of life for the blending of chemical materials and for on-line control of the cement kiln. Accordingly, the cement application is selected for further presentation in the paper. This illustrates the trend progressing from control of single loops on process variables toward the objective of total control of the product quality. The economic justification for instrumentation, centralized control, automatic control and computer control is .discussed with reference to savings in fuel, maintenance, operating labour, depreciation, power and product quality improvements."

Jan 1, 1967