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By Abraham B. K, Jensen B, Gillies A. D S

The aim of the research was to investigate the feasibility of using an impedance cell and ratio-transformer bridge to measure solids content in coal slurry pipelines. It appeared that this technique could be developed to measure variations in conductance which correlate with solids content. Successful implementation of the measurement technique would have a variety of applications in existing coal wash plants and the potential for automatic process control. A small pilot plant was designed for a feasibility study. This was a closed loop system in which the coal was uniformly dispersed in a tank with a variable speed agitator and then circulated through an external pipe returning to the top of the tank. The impedance cell was located near the end of the external pipe. Slurry concentrations were varied from clean tap water to 50 per cent solids by weight with the addition of weighed quantities of dry coal dust. Ratio-transformer bridge measurements showed that variations in individual observations were equivalent to measurement errors of about two per cent. These probably reflect variations in concentration of the mixture in the pipe. Data for increments in concentration of one per cent indicate that this is about the limit of resolution of the current system. The paper discusses the principles of operation of the impedance cell and measurement system. Results from the pilot study and proposed improvements in the impedance cell design are examined.

Jan 1, 1995

The implementation of a process information management system (PIMS) is to provide a single online, real-time information system. This system provides a unique and completely open view for everyone, based on the key business drivers. It is structured around the three key concepts: process, maintenance and stocks. It combines numerous applications and provides accessibility to common tools and reports, through a web-based user interface, for every one from the floor operator to the General Manager. This æunique and commonÆ view displays raw, online process information that provides a quick health check of the operation at a glance, highlighting areas that require further investigation. The system is based on a hierarchical system of views, from the overview of the whole plant flow sheet to the more detailed operational shop view. It provides a synthetic view between continuous and batch operations, enabling the tracking of each batch produced. The batch view displays the critical batch components, and a comparison with each component of an ideal batch. This enables detailed analysis of each batch to identify areas of improvement. The information system will consist of an online reconciliation of stocks and flow data. This enables focus on the recovery of each process unit on a regular basis. This paper discusses the design strategy for the Process Information Management System, to ensure a unique and open view on the key business drivers is achieved and implemented successfully.

Jan 1, 2005

By G M. Evans, C M. Phan

This paper presents an analysis on the dynamic adsorption of frothers and collectors onto air bubbles in flotation. The analysis was carried out using the theory on the surfactant transfer by diffusion and adsorption. The bubble size was considered when solving the diffusion equation for the dynamic surface excess. The adsorption kinetics was modelled employing the Langmuir adsorption isotherm and its extension with the inclusion of the lateral interaction of the adsorbed molecules (the Frumkin adsorption isotherm). The numerical computation was applied to solve the governing equations. The dynamic adsorption of the surfactants was measured in terms of the dynamic surface tension for sodium dodecylbenzene sulfonate (SDBS) and Dowfroth 250, using pendant bubble tensiometry. The results show that for air bubbles with diameter of the order of 1 mm, the bubble size effect on the dynamic surface tension is small and the solution of the diffusion equation for a planar gas-liquid surface can be used to describe the dynamic adsorption onto the air bubbles. The experimental data obtained with SDBS were well described by the Frumkin adsorption isotherm and the molecular diffusion. The model description for the experimental data obtained with Dowfroth 250 required the kinetic equations. The paper is relevant for further analysis of the role of the adsorbed surfactants in the particle collection.

Jan 1, 2005

By E C. F Hamman

Sunrise Dam Gold Mine is a large open pit mine 730 km NE of Perth, Western Australia. Contract mining commenced in the open pit in September 1996 in lake clays and saprolites with the first fresh rock mined late 1999, and the underground starting the first decline in October 2003. By May 2007, over 150 million cubic metres of material had been mined and the pit was 360 m deep with 80 m remaining before reaching the planned final depth in early 2008. A final cut-back in the northwest will commence in late 2007 with open pit mining in the Mega Pit expected to conclude in late 2010. The challenges of developing the pit can be divided into three phases:Soft materials û mining was in multiple staged pits and cut-backs in lake clays, saprolites, weathered material. The varying characteristics had a significant impact on mining methods and slope stability. Structural û mining was gradually exposing more fresh rock and the drive was to understand how major structures and lithological contacts impact on local and large-scale stability. This had a significant influence on mine design and scheduling. Slope angles û achieving the final slope angle is critical. This is done through application of high standards of final wall establishment and proactive geotechnical hazard identification and management. This includes dealing with the rapid rate of descent, interaction with underground excavations and managing rock fall risk. The paper discusses each of these phases, highlighting the geotechnical controls implemented to date, looking at their success and impact on mining.

Jan 1, 2007

The first 12 m diameter rakeless thickener in the Australian gold mining industry was installed to treat plant tailings at the St Ives gold plant in April 2000. The plant processes approximately 3.2 M tonnes of ore producing about 430 000 oz of gold per annum using conventional crushing, grinding, gravity and carbon in pulp processing methods.The main benefit sought from the thickener was to improve water recovery in the plant and provide water for a 55 000 oz per annum heap leach operation. The thickener design indicated that more than 128 m3/h of overflow water could be returned directly into the plantÆs water circuit, relieving the demand on the borefields. The resultant surplus in the water circuit would then be available for the heap leach project. Based on laboratory and pilot plant scale tests conducted by EIMCO the thickener was designed to handle up to 700 m3/h of tailings slurry (450 tph of solids) with a 40 per cent oxide component in the ore blend. The normal plant throughput is 565 m3/h of slurry (400 tph of solids). Gold mineralisation in most areas at St Ives comprises quartz-sulphide vein and breccia lodes with common albite-biotite-chlorite alteration assemblages. There are well developed supergene gold horizons in the clay-oxide profile above most of the deposits (Osborne, 2002). This results in a wide variety of ore types being treated. At times 40 - 50 per cent of the ore may be oxide in nature. After some commissioning difficulties associated with instrumentation, the thickener has performed satisfactorily although it has not reached its design capacity. The maximum density achieved under normal operating conditions with 20 per cent oxide ore is about two per cent below the design. The thickenerÆs performance deteriorates further with increasing amounts of oxide ore in the blend. The thickener has provided sufficient water for the successful operation of the heap leach and has also provided some down stream benefits for the gold plant by way of pH and cyanide conditioned thickener overflow water.

Jan 1, 2002

It is a commonplace of our industry that prices of most minerals have been historically weak during the 1980s. The International Monetary Fund's index of prices of metals fell 25 per cent between 1980 and 1982, rose slightly in 1983, and has since fallen further. In December last year it was 37 per cent below its 1980 average. The few temporary exceptions to the mineral industry's malaise highlight the excess capacity, which largely explains the weakness of prices. The industry has painfully come to recognise that more satisfactory prices will not be restored until supply capability and demand move back into better balance. Mine capacity was installed in the expectation of much faster growth of demand than has occurred. For a variety of reasons mine and plant closures have been insufficient to restore equilibrium to the market-place. The industry may, therefore, have to resign itself to continued weak prices for some years more, at least by the yardstick of the 1970s. Growth rates of demand have slackened off in line with economic activity, and in response to continuing substitution and technological improvements. To the extent that the recent weakness of oil prices stimulates the industrial countries' activity, demand for non-fuel minerals may grow faster than most forecasters now predict. It is, however, much too early to say how long the weaker oil prices will persist, and even more difficult to estimate their probable effects. In typical post-war business cycles the usual response to recession was to batten down the hatches, and ride out the storm. Sooner or later, and probably sooner, demand resumed its previous trend path, and prices recovered. The market, in effect, bailed mines out of trouble; the more efficient could make attractive pre-tax profits whilst even the poor to mediocre could earn a satisfactory living. Prices rose at least as fast as general inflation, and in the early 1970s much faster. In retrospect those price rises of the early 1970s were historically abnormal but they did not appear so in the prevailing inflationary climate of the time. When the market failed in the early 1980s many of the hardest hit companies looked for scapegoats.

Jan 1, 1986

Downstream value-adding is a strategic issue for a country like Australia, which has a resources-driven sector of a scale that has significant impact on the national economy. The question of why producers are not doing more to ævalue-addÆ is often asked. In Australia this debate takes place within the context of: an era of unprecedented growth in demand for resources driven by the rapid urbanisation of China, India and others;impending legislation and uncertainty around carbon pricing;rapidly rising energy costs;significant supply-side shortages including infrastructure, skills and manufacturing capacity; andsignificant industry consolidation of primary resource producers with commensurate improvements in market power.There are several examples of resource-based industries which have developed their business along the complete value-chain; for example large oil and gas producers successfully span upstream and downstream operations including refining and petro-chemicals as well as retail distribution of fuel and other products. Relevant frameworks that provide insight and understanding into the strategic issues around value-adding are reviewed and examples of the application of these frameworks to companies and industries which have successfully adopted a strategy of integrating along the value-chain, as well as those players who have focused on parts of the value-chain are presented. The issues around value-adding in Australia are then reviewed with reference to these frameworks and it is concluded that the issue is a conflict between the objective companies who wish to maximise financial value versus the desire of governments to increase economic benefits. An approach to aligning these objectives is proposed.

Jan 1, 2008

Urban railway systems need high invest- ments, especially if their routes and stations have to be placed in the subsurface. In the FRG the construction and equipment cost of urban underground railway systems are in the range of 60 to 100 Mill DM per km tunnel. For this reason, track sections on the surface and on elevated structures are used as far as that is possible. Considering whole systems, the costs are in a range from to 45 Mill DM per km length for a metro system with about 80 % of its tracks and stations in tunnels and from 20 to 25 Mill DM per km for a light railway system with about 25 % subsurface infra= structure. The amount of route lengths in tunnels depends on the size of a city, the situation regarding above ground structure and free space on the surface, the level of service quality which has to be achieved with the railway system etc. Despite of the urgent needs to improve the transport conditions there very often arise doubts if an urban railway system is really necessary and can be justified in an economic sense. The experience from many cities around the world shows, that there arise a lot of benefits from urban railway systems, especially with larger sections placed under- ground. They are to be found in the interests of the operator (f.e. operating costs), the user (travel time, quality of service etc.) and regarding social aspects (environmental protection, accidents, consumption of energy Etc.).

Jan 1, 1987

By J J. Cilliers, K Hadler

Froth structure and stability are known to play important roles in determining mineral flotation recovery and selectivity. However, measuring froth stability in a consistent manner remains a significant challenge, especially at an industrial scale. Following preliminary tests on a copper concentration plant, a quantitative dynamic stability measure is investigated in this study in order to extend the results over a wider range of conditions and on a different orebody. The technique is based on the Bikerman foam test and uses a non-overflowing froth column to quantify froth stability. Experiments were carried out using an automated version of the froth stability column under different operating conditions. Air flowrate was the key operating variable. Tests were reproduced on a single flotation cell of a Platinum Group Metals concentrator. The froth stability factor, , was measured for each operating condition, and compared with the air recovery in the cell, , which was measured using image analysis. The froth stability column results gave the same trends as image analysis. In particular the froth stability factor was found to be linearly related to the actual fraction of air overflowing the cell. The metallurgical results clearly indicated that changes in air flowrate result in variations in flotation performance that can be attributed to changes in froth stability. The results showed that high froth stability conditions occur at intermediate air flowrates, and result in improved flotation performance. It is found that the froth stability column is a simple, cost-effective and reliable method for quantifying froth stability, and for indicating changes in flotation performance.

Jan 1, 2005

THE following paragraphs represent an endeavour to describe, briefly the equipment used for the manufacture of sulphuric acid and superphosphates by the Corporation.SULPHURIC ACID PLANTS.Two separate units are in operation, No. I Plant working on sulphur dioxide generated from pyritic ore, No. 2 Plant working on sulphurous gases obtained from the Huntingdon-Heberlein desulphurizing process. The latter plant is unique in being the first installation for the successful use of these gases.

Jan 1, 1918

By W B. Edgar, I M. Platten, C A. J Towsey, B W. Cuffley

The evaluation of historical goldfields has been common over the past 15 years, reflecting changing economic conditions, improvements in knowledge and technology and lack of greenfield sites. Many goldfields comprise narrow gold-quartz veins, which are structurally complex with an irregular distribution of gold, have variable geometry and architecture and display late deformational effects. The study of historical mine records can be an important tool during early and advanced project evaluation, since it contributes to understanding the orebody, exploration target size and setting expectations. Mine records include documents such as plans, sections, reports, news cuttings, production tabulations, etc. A major advantage for the modern explorer is the capability of computer modelling to display this data in 3D. Historical records can give the explorer substantial information on various deposit characteristics, not least grade and geological continuity, geometry and architecture, mineralogy, metallurgical properties, bulk density and ground conditions. From an evaluation perspective, historical records can be used to support a Mineral Resource estimate, though its application will depend upon the quality and quantity of the data and judgement of the Competent Person. Effectively used, historical records can reduce geological uncertainty and focus evaluation efforts û thus reducing project risk.

Jan 1, 2009

By Blaskett K. S

The physical properties of monazite and the minerals with which it is associated in east coast beach sands are studied and discussed. Possible means for improving recovery are examined. In particular, it is suggested that the practice of splitting the heavy mineral concentrate into two parts as a preliminary to treatment in separate "rutile" and "zircon" mills can be modified in a simple fashion by the addition of an extra magnetic separation stage so as to aid monazite recovery.INTRODUCTIONBeach sand deposits on the east coast of Australia are a major source of rutile and zircon, and supply 80 per cent or more of world requirements. The deposits also contain a small amount of monazite, averaging about 0.5 per cent of the total heavy minerals. Yet despite a steady price in recent years of £150-160 per ton, monazite production has remained relatively small.On the basis of rutiIe production, potential monazite production on the east coast was about 1,500 tons in 1956, but only 102 tons of high-grade concentrate was produced. The main deterrent to increased production has probably been the capital cost of the necessary equipment. Separate electrostatic and magnetic equipment and separate table concentration and drying constitute a considerable outlay for a by-product contributing 4 to 5 per cent of the revenue from rutiIe.It is the purpose of this paper to discuss monazite concentration generally and to suggest modifications to flowsheets, which may facilitate monazite production while maintaining the main objective, simple and cheap means for maximum rutile production.

Jan 1, 1958

With the post-war expansion of mmmg activities on its Western group of mines, the management of Lake View and Star Limited has commenced a project for the improvement of underground ventilation.The major part of this project is to provide adequate return airways for the ventilation of the deep levels. To this end, the Ivanhoe South Extended shaft is being enlarged, and ultimately an exhaust fan with a capacity of 180,000 cu. ft. of air per minute will be installed at the shaft collar.Prior to 1932, the shaft was used exclusively for baling water from the 800 and 2,000 ft. levels. These two levels are the only ones connected to workings from the Horseshoe lease. After the installation of pumping plant at the Horseshoe Main Shaft, baling was discontinued, and the water was graVitated from dams to the pumps on the 1,000 and 2,000 ft. levels.Water makes into the shaft, through a series of fault planes, between the 600 and 1,500 ft. horizons. The total flow is 16 gal. per minute, of which approximately 7 gal. per minute graVitates to the 800 ft. level. As a big proportion of the water dropped uncontrolled through the shaft, a downcast current of air approximating 20,000 c.f.m. was induced. This air ventilated a limited area of workings in the Horseshoe lease, between the 2,000 and 2,360 ft. levels.In 1938, it was decided to reverse the direction of the airflow in the shaft. Work was carried out to pipe the...

Jan 1, 1948

By A. W. CAMERON

Over a 4 hr period of steady plant operation samples were taken at regular intervals from points within the grinding and flotation circuits. Size fractions of each composite sample were analysed for lead and zinc values and a comparison made of the behaviour of the lead, zinc, and gangue minerals, size by size throughout the whole circuit.Analysis of the breakage behaviour using dynamic mathematical models gave the rates of breakage of each size fraction of each main component. Simulated grinding experiments showed that the main grinding circuit had some reserve capacity.In the lead flotation circuit all lead values between 150 mesh (Tyler) and 5 microns had excellent flotation characteristics, and a major proportion had a high rate of flotation which was practically the same for all sizes. Increase in overall lead recovery would require improvement of the flotation behaviour of ultra-fine lead minerals. These were slow floating and were responsible for approximately half the lead losses in the final zinc concentrate and one-third of the lead losses in the final tails.All sizes of zinc values between 100 mesh and 7 microns floated well and the performance of the zinc flotation circuit was mainly limited by the relatively poor flotation of the very fine zinc values. Approximately 60 per cent of the zinc lost to the final tails lay within the minus 7 micron fraction.The overall flotation conditions were conducive to very good selective flotation of the major proportion of the values and limitations in metallurgical performance were mainly due to the properties of the ultra-fines.

Jan 1, 1971

By D Espinoza, I Rees, J Pocoe, P Collier

P Collier, I Rees, J Pocoe and D Espinoza

Mar 22, 2022

By V P. Beskrovnaya

Tests for the development of a metals recovery technology from samples of a Russian gold-bismuth deposit were carried out. Gold, silver and bismuth assay reported 5.6 g/t, 3.0 g/t and 0.08 per cent, respectively. Two flow sheet options were pilot plant tested: gravity/cyanidation of gravity tailings with subsequent flotation of cyanidation/carbon-in-pulp (CIP) tailings, and gravity/flotation concentration with cyanidation/CIP of concentrates. Option 1 results showed lower gold, silver and bismuth recoveries (81.3 per cent Au, 55 per cent Ag and 74.0 per cent Bi) due to low flotation efficiency for cyanidation tailings. Therefore, a flow sheet involving gravity/flotation concentration to produce bismuth-gold concentrates (0.8 per cent Bi) with subsequent cyanidation/CIP was recommended. Gold, silver and bismuth recoveries obtained by this method to the combined gravity/flotation concentrate were 90.2 per cent Au, 83.3 per cent Ag and 80.2 per cent Bi of the ore, respectively. Overall gold, silver and bismuth recoveries were 83.0 per cent Au, 40.5 per cent Ag and 80.2 per cent Bi, respectively. Gold and silver recoveries to the cathode precipitate were 92 per cent Au and 48.6 per cent Ag (per operation). Reagents consumed for flotation were 0.1 kg lead acetate/t ore, 0.4 kg butyl xanthate/t ore, 0.2 kg T-80 frother/t ore, 0.02 kg sodium hexametaphosphate/t ore, 0.15 kg copper sulfate/t ore. Reagents consumption for cyanidation was 0.42 - 0.48 kg NaCN/t ore and 0.2 kg CaO/t ore. It was recommended to deliver bismuth concentrates after hydrometallurgical treatment to a smelter. Overall bismuth recovery including bismuth recovery achieved by pyrometallurgy was 60.0 per cent. However, it was obvious that delivery of bismuth concentrates to a smelter and their commercial treatment would be very expensive due to relatively high mass pull of bismuth concentrates (7.6 per cent of the ore weight). For this reason, thiourea leaching and hydrochloric acid leaching with subsequent cyanidation/CIP were investigated as alternatives to cyanide leaching. These two alternatives were proposed to enable optimal recovery of valuable metals from concentrates on-site. Recoveries obtained by thiourea leaching were 91.2 per cent Au, 90.5 - 91.9 per cent Bi and 77.0 - 78.1 per cent Ag. However, that method required considerable capital and operating costs. As an alternative, hydrochloric acid leaching with subsequent cyanidation was investigated. Test results showed improved gold, bismuth and silver recoveries, which were 94 - 95.9 Au per cent, 94 - 96 Bi per cent and 76 - 78 Ag per cent, respectively. Hydrochloric acid consumption was 100 kg/t concentrate or 7.6 kg/t ore. Current efficiency during electrowinning was about eight to 12 per cent. A recommended flow sheet involving hydrochloric acid leaching of concentrates, electrowinning of bismuth from solutions, recycling solutions after electrowinning and cyanidation of hydrochloric acid leaching cakes is described. Overall recoveries achieved by the proposed flow sheet were as follows: 84.8 - 86.5 Au per cent, 75.8 - 76.9 Bi per cent and 63.2 - 64.9 Ag per cent. Based on results from these tests, initial data for a bankable feasibility study and plant designing were developed.

Jan 1, 2007

By D Bradshaw, J R. R de Villiers

The non-stoichiometric sulfide mineral pyrrhotite (Fe(1-x)S), common to many nickel and platinum group element (PGE) ore deposits, occurs in varying crystallographic forms with the different types exhibiting subtly different physical and chemical properties. These differing properties are likely to influence the flotation performance of pyrrhotite, which in the case of PGE operations is actively recovered, whereas in nickel operations pyrrhotite is depressed. In this study, examination of natural pyrrhotite samples from Southern African and Canadian nickel and PGE ore deposits revealed a variety of pyrrhotite compositions in terms of iron content (Fe7S8, Fe9S10, Fe11S12) and solid solution nickel concentration. Pyrrhotite composition was correlated with its mineral association depending on whether non-magnetic pyrrhotite occurred in conjunction with troilite, non-magnetic pyrrhotite occurred as single phase pyrrhotite, magnetic pyrrhotite occurred as single phase pyrrhotite or whether the two phases; magnetic and non-magnetic pyrrhotite co-exist. Subsequent microflotation tests of selected single phase pyrrhotite samples revealed that the non-magnetic pyrrhotite is slightly more floatable than magnetic pyrrhotite. Microflotation tests also showed that varying flotation responses occur between differing magnetic pyrrhotite samples. These differences in flotation performance are postulated to be a result of the effects of varying pyrrhotite crystallography, trace metal content and mineral association on pyrrhotite oxidation, formation of surface species and subsequent adsorption with xanthate collector.

Jan 1, 2008

By R-H Yoon

A turbulent flotation model has been developed by considering the subprocesses of collision, attachment, detachment, and froth recovery. AbrahamsonÆs model (1975) of infinite Stokes number is used to model collision, while the attachment and detachment subprocesses are modelled by considering the kinetic energies required to overcome the energy barriers and the work of adhesion, respectively. The energy barriers are determined by considering various surface forces, including electrostatic, dispersion and hydrophobic forces, while the kinetic energies are determined from the particle velocities at close separation distances from air bubbles. The latter has been determined by modifying the turbulent root-mean-square (RMS) velocities of Liepe and Moeckel (1976) and Schubert (1999) in view of a lubrication theory. In calculating the RMS velocities, it is assumed that a flotation cell is subdivided into low and high energy dissipation zones. The model predictions made by varying various hydrodynamic and surface chemistry parameters are consistent with flotation practice.

Jan 1, 2005

Botanical exploration has identified many plant species that naturally accumulate very high concentrations of elements, particularly heavy metals. The enormous potential applications of some of these species to remove metals from soil (phytoextraction) are slowly being realised. The discovery of hyperaccumulation has resulted in considerable research into applications for removing contaminants (phytoremediation) or more importantly, in the context of this discussion, for commercially æfarmingÆ metals (phytomining) from metal-bearing soils. Currently published phytoextraction models estimate Ni yields using Berkheya coddii (a South African nickelophyte) are approximately $US 750 ha-1, excluding the cost of processing. Research indicates that B. coddii will also accumulate significant amounts of Co, resulting in a considerable increase in the value of the crop. Modification of the substrate by acidification, fertilisation and/or chelation indicate fruitful avenues for improving this yield by increasing the extractability of the target element, elevating biomass production rates and/or rendering other contained heavy metals extractable. Plant uptake of more insoluble elements, such as Au, may be induced in many plant species using chemical compounds. These chelates applied to the soil, form soluble complexes with poorly soluble metals forcing them into the soil solution. Plants may then accumulate these metal complexes through transpiration. Research has achieved foliar Au concentrations of 78 mg kg-1 in Iberis intermedia, 56 mg kg-1 in Brassica juncea and 9 mg kg-1 in B. coddii (on a dry weight basis). Therefore in theory B. coddii could phytomine a soil containing modest concentrations of Ni, Co and Au to yield 116 kg Ni, 36 kg Co and over 6 oz Au ha-1 at a current value of $US 4000. Root crops have also shown promise in chelate assisted Au accumulation (eg 6.8 mg kg-1 in Beta vulgaris and 118.5 mg kg-1 in Raphanus sativus). Phytoextraction, in its varied applications, is rapidly coming of age as a technology having considerable potential for application in environmental science and the minerals industry. Phytotechnology employs unique plant biochemical behaviours in the rhizosphere, driven by the sunÆs energy, to seek out and concentrate low levels of heavy metals at very low cost.

Jan 1, 2002

It may at first sight appear somewhat presumptuous for the writer to attempt to discuss a subject in which he cannot pretend to possess any special scientific training; but a sufficient apology can surely be found in the fact that a very large percentage of the accidents from explosives occurring in metalliferous mines is traceable to the ignorance of the characteristics of these compounds by the miners who have to handle them, and to their deliberate disobedience of the rules laid down for their guidance by the manufacturers, the government regulations, or the special rules of the mines.The only method which promises any possibility of improvement upon these conditions is to substitute reason and understanding for the rule-of-thumb principle which says "you should do this" or "you should not do that." In the one case his own knowledge and intelligence enables the miner to avoid any dangerous practice in the other his inclination prompts him to do anything which will save time, provided he is not found out or at best trusting to his memory to tell him what is dangerous, without the reasoning which makes that memory easy.Another evil of rule-of-thumb knowledge is that, from its very nature, it prevents adaptability, and so we find that old miners, who learnt blasting in the days of black powder, cannot understand why high explosives do not require heavy tamping, or because copper bars are permitted in tamping powder they should not be used with other explosives...

Jan 1, 1903