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By John Henry Harden

This shaft, located in the northern anthracite coal-field about 2300 feet southwest from the court-house at Wilkes-Barre, in the County of Luzerne, Pa., is the property of the Lehigh & WilkesBarre Coal Company. The sinking and cribbing to the solid rock (see isometrical view on Plate IX) was conducted by Mr. W. W. Kenrick. Dimensions of the earthwork to the foundation of the cribbing, 51' 2" long, 17' 4" wide, 31' deep. Total amount of excavation in cubic yards, 998.5. Dimensions within the permanent cribbing, 45' 4" long, 11' 16" wide, 31' deep, divided into six parts by buttons 8" x 12", each division, 7' x 11' 6". Permanent cribbing 12" x 12"; temporary cribbing 8" x 10" ; backing, 3" thick ; clay puddle to exclude surface water, 12" thick; conductors, 8" x 5"; lining, 1" thick from top to bottom of the shaft. In the latter part of the year 1871, Mr. H. Murray & Son contracted with the company for the continuation of the work at the rate of four hundred dollars per yard in depth, to a point 100 feet below the Hillman seam of coal; for the succeeding 100 feet the price to be increased twenty-five dollars per yard, and so on until the bottom rock of the Baltimore seam of coal was found. The size of the shaft within the cribbing timbers is 45 feet 4 inches by 11 feet 6 inches, having six divisions of equal dimensions, 7 feet by 11 feet 6 inches, giving room for what is known as the "standard diamond " car, whose capacity when level full is 100 cubic feet, but when loaded by the miner 4 inches above the top contains 112 cubic feet." Two divisions of this shaft are intended for hoisting coal from the Hillman seam, two from the Baltimore seam, one for ventilation, and one for pumps. The works were planned for two pairs of direct-acting, high-pressure engines, twenty-four boilers, and for an estimated output of 2500 tons of coal per day from the two seams.

By D Monaghan

Pumping water for dewatering and water supply is a major component of electricity consumption at mining operations and hence is a significant contributor of greenhouse gas emissions. Pump systems at a typical mine site can be broadly split between above ground centrifugal pumps (generally used for water transfer) and submersible borehole pumps (generally for dewatering and/or water supply). In contrast to above ground pumps, submersible borehole pumps can be subjected to varying duty points (total pumping head and flow requirements) as a result of changing bore water levels and yields, particularly in mine dewatering bores. Typically, much higher pumping rates are required at the commencement of dewatering to remove groundwater storage and to intercept sufficient groundwater throughflow to achieve target drawdowns. Once target drawdown levels are reached it often only requires much lower pumping rates to maintain target drawdowns. Pumps sized to remove the large initial volumes of stored groundwater often end up too large for the lower flow rate required for æmaintenance pumpingÆ. This often results in pumps operating inefficiently, a problem which can be made worse when pumps are throttled to reduce the pump output to better match the reduced bore yield. Current standard operating practice places little emphasis on the electricity consumed by pumps, with the focus often being on minimising capital expenditure (æIf it ainÆt broke donÆt fix itÆ). Submersible pumps can have extended service lives of ten to 20+ years. However as the capital cost of a pump typically represents only five per cent of the life cycle cost, the vast majority of the life cycle cost is energy usage.Through the implementation of a regular review of the operation of borehole pumps, significant reductions in electricity use and associated greenhouse gas emissions can be achieved without impacting the dewatering schedule. In most cases, the capital cost of replacing pumps is more than offset by savings in operating costs. These potential savings become even more significant when considering proposed future carbon tax levees.This paper presents examples of the opportunities for significant reductions in energy, greenhouse gas emissions and overall costs that can be achieved for a range of dewatering scenarios.

Jan 1, 2009

IN any assay office it is of paramount importance to keep the men interested in their work; and in order to do this, men on routine work, such as lead, zinc, and sulphur deterrrrinations, slag analysis, etc, should be changed around monthly. This gives some variety and helps to keep a man's interest on his work, so that better work results. It may be maintained that to keep a man on the same class of work indefinitely makes him more expert at his work. This is certainly true; but in assaying, where accuracy is so essential, it is absolutely necessary for a man to keep his mind on the work, and not 'get' into a mechanical method of working. He is also on the alert to discover means for shortening his analytical methods, and his capacity forwork is increased. Another advantage is that the men get a good all-round training, and one is never at a loss to replace a man on any class of work when he is absent from any cause. This tends to smoother and more efficient running of the assay department. In industrial assaying it is often advantageous to have a result quickly, so that it will be of maximum benefit in the running of some part of the plant, In such a case it pays to sacrifice a little accuracy to speed up a method. The shortest method is less costly, and a quick approximate method is all that is required to give the superintendent the requisite information. Time is thereby saved, and the cost is less. In carrying out assaying for any large industrial plant, such as a smelting works, there is always a tendency for superintendents running the different departments to send in more samples for assay than are absolutely necessary when no system of costing is in operation. Some of these samples may involve a lot of work and heavy expenditure, as, for example, the estimation of only one impurity in a sample of refined lead. If the superintendent knows that the cost of assaying all samples sent in by,him is charged up directly against...

Jan 1, 1922

By A. M. Nicholas

WHEN attempting to lift mill pulp containing a considerable percentage of wolframite, in an ordinary bucket elevator, difficulty was encountered from the tendency of the tungsten minerals to settle, on account of their high specific gravity. Lifts not exceeding 20 ft. (6m.) could be accomplished without particular difficulty, because there was insufficient time for consolidation of the heavy minerals in the bottom of the bucket; but with higher lifts, the heavy tungsten minerals would settle so solidly that when the bucket turned over at the top of the elevator the contents could be only partially dumped. In this case it ,was necessary to lift the material a distance of 34 ft. (10m.); hence some means had to be adopted to prevent settling, at least to such an extent that the material could be dumped from the buckets. To reduce the carrying time to a sufficient extent would have required a belt speed of 475 ft. (144.7m.) per minute, which was not feasible. It was decided to try, by vibrating the belt about midway of its span, to keel) the material sufficiently agitated during elevation to prevent settling. Underneath the rising side of the belt was placed a 12-in. (30.48-cm.) idler pulley, 18 ft.-(5.5 in.) up in the total lift of 34 ft. The idler pulley was set eccentric by 3/4 in. (19 mm.) and it was hoped that the vibration thus imparted to the belt, running at a speed of 280 ft. (85 m.) per minute, would prevent settling in the buckets. It was found that the pressure of the belt on the idler, due to the small inclination of the elevator, was not sufficient to overcome sliding on the idler, and the agitation was insufficient to accomplish the desired purpose. The idler was then connected to the drive shaft of the elevator through an intermediate pulley, gearing down to a speed of 20 r.p.m., so that a positive vibration was imparted to the belt; this imparted enough motion to the belt to prevent settling and the contents of buckets clumped satisfactorily.

Jan 2, 1918

The pattern of the coal industry west of the Mississippi River, so far as its history is concerned, is entirely different from that to the east of the "Father of Waters." When the Louisiana Purchase was consummated, one of Jefferson's first thoughts was to ascertain what sort of a country had been purchased, and to that end he sent Lewis and Clark to ascend the Missouri River and to reach the Pacific Ocean if possible, but above all to bring back a report showing the character of the country, its mineral and other resources, inhabitants, etc. This first expedition was supplemented by others to various parts of the vast domain for the same purpose; years later, when transportation routes were necessary to hold and develop the western country, a number of expeditions were sent to explore possible routes for railroads. The records of nearly all of these explorers, as will be shown later, contain references to coal in many localities, the possible value of which was realized but its potential value remained dormant for many years until increasing population and methods of transport made markets available. Missouri was the first state west of the Mississippi in which coal was produced and the names of a number of places show that the French were familiar with the coal deposits there. Lewis and Clark, soon after they left St. Louis, passed "a remarkable Coal Hill on the Larboard Side, called by the French Carbonere, this hill appeares to Contain great quantity of Coal."1 This hill was about seven miles below St. Charles. No other outcrops were seen by them until they had passed the present limits of the state. The Louisiana Gazette of April 9, 1805 contained an article on "The Missouri," author not stated, which said, "the short stay we have generally made among the savage nations has prevented us from making those researches, which would have supplied us with a more extensive information respecting the various mines found on the borders of the Missouri; we know with certainty only those of iron, lead and coal." In 1806 Pike passed through Missouri on his tour to Mexico. On August 17th, along the Osage River he remarked, "here the river-bank is

Jan 1, 1942

By N. Cabrera

IN a recent paper Kuczynski' studied the rate at which the crack between a metallic plane and a spherical particle of the same material is filled up gradually when heated at temperatures near the melting point. If x is the radius of contact between plane and sphere (fig. I), Kuczynski shows experimentally that x5 = At [1] where t is the time. Assuming that the mechanism of transport of matter is the volume diffusion of vacant lattice sites, he is also able to prove Eq 1 theoretically. The constant A contains as a factor the self-diffusion coefficient of the metal and he shows that the values for this coefficient deduced from his experiments yield the same activation energy as that calculated by other methods, which is a confirmation of this point of view. Kuczynski has also considered theoretically the law of growth of x which would be expected if surface diffusion were the important mechanism. He suggests that x should then obey a law of the form x7 = At, and claims to be able to decide the mechanism involved from the observed law of growth., The purpose of this note is to prove this incorrect. On the contrary, when the mechanism is surface diffusion Eq 1 is also obeyed, but with a different constant A. Following Kuczynski, we suppose the bottom of the crack (surface A A) to have an average radius of curvature p. As a result of this curvature the concentration of adsorbed atoms in this surface, n(p) per cm2, will be smaller, and the concentration of vacant lattice sites in the neighborhood, N(p) per cm3, will be larger than the corresponding concentrations, n(w) and N(w), for a flat surface. For all practical cases we can write Thomson's formula in the form n(co)— n(P) N(P)—N(cc) _ 2a-a" n(oo) JV(co) kTp [2] where u is the surface energy of the metal and a the interatomic distance. 1. Let us now consider the mechanism of surface diffusion. We suppose the concentration of ad-

Jan 1, 1951

From the early part of the thirteenth century bituminous coal was called "sea coal" in England, from the fact that the coal seams in the Fife and Northumberland fields outcropped on the shores of the North Sea and wave action and erosion resulted in lumps of coal being found in large quantities along the shores. These were gathered by women and children and sold for fuel to replace wood. Coal first reached London by sea, and there was a "Secole Lane" in that city in 1228. The term was gradually applied to all coal and for some hundreds of years all coal in England was called "sea coal", and the term is not yet obsolete there. Another reason for the use of a defining word was the fact that from time immemorial, in England and elsewhere, the word coal meant char-coal, or coal made from wood, as this was the common fuel of those times when anything other than natural wood was burned. The biblical references to coal all mean wood-coals or charcoal, and one must be careful in writings prior to at least 1750, when "coal" is used to be sure that it means stone, or mineral coal, rather than wood or charcoal. "Sea-coal" was in common use along the Atlantic seaboard until after about 1780; the first map showing coal in Pennsylvania, Ohip and Kentucky, made as of 1750, used the term "sea-coal here."2 In the interior stone coal was used by the early writers almost entirely, partly to differentiate it from charcoal, but largely because it was found with stones and rocks, and in most places then had the same value. "Fossil" coal was used by Hamilton in 1790. Jefferson called it mineral coal and pit coal in 1781. The term mineral coal was usually used in the governmental references to it as late as 1850, but the present use of bituminous coal began as soon as anthracite came on the market in 1820. Both mineral and stone coal still survive in the laws of several states specifying the weight of a bushel of coal.

Jan 1, 1942

By N. Coulson, P. Ledwaba

"The University of the Witwatersrand presents an accredited four-course training programme for community relations practitioners (CRPs). Between May 2013 and October 2014 six courses were facilitated for 145 participants, of whom 82% were from sub-Saharan Africa, 62% worked in mining, and 58% worked directly with communities. Thematic analysis of the comments of course participants collected during course exercises found that there were a set of coherent drivers for resilient companycommunity relationships, but that the restrainers to resilient relationships were often context-specific and dominated by politics. CRPs reported facing as many difficulties in the internal company environment as in the external environment. These findings for CRPs in Africa resonate with those worldwide.InroductionMuch has changed in how the extractive industry responds to social and community issues. There has been a growing prioritization of community-related issues within the extractive industry globally (Kemp, 2010; Tatar, n.d.). According to Kemp (2010) this can be attributed partly to escalating pressure from local-level stakeholders to push mining companies to take greater responsibility for the social, economic, and environmental impacts of mining. Securing and maintaining the social licence to operate is ranked fourth in terms of the top risks facing the mining and metals industry in 2016, up one place from 2015 (Ernst & Young, 2016).Conflicts between local communities and large-scale mining companies arise because of the social, environmental, and economic impacts of mining. Worldwide, large-scale mining companies have a poor reputation amongst communities, including those in Africa (Gilberthorpe and Banks, 2012; Kemp and Owen, 2013a; van Wyk, n.d.). For mining companies, conflicts for whatever reason, result in loss of productivity, lost opportunities, lost time, and adverse impacts on reputation (International Council on Mining and Metals, 2015). Conflicts also have a significant financial impact on mining operations (Franks et al., 2014). Davis and Franks (2014), estimated that US$10 000–50 000 is lost each day when a project is delayed during the exploration phase, and about US$20 million per week when in operation. Today these costs could be expected to be higher due to increasing input costs."

Jan 1, 2017

By Allan J. Clark, W. J. Sharwood

When the cyanide process came into general use, late in the nineteenth century, chlorination was quickly supplanted, but amalgamation yielded place more slowly, being still the major process at many plants, where it is followed by cyanidation of the tailings. The research work of the Denny brothers in South Africa' was probably the most important contribution of its time to the metallurgy of gold. By grading analyses of mill products, they pointed to the necessity of fine grinding to accomplish maximum extraction by cyanide. The work here described is merely an extension of the Dennys' method. Developing the fine-grinding principle, the steps of "crushing in solution" and of "all-sliming" were logical sequels, though both had been attempted early in the history of the cyanide process. Crushing in solution introduced certain complications in amalgamation; when "all-sliming " was adopted it was observed that the omission of amalgamation did not materially affect the total recovery. Thus the field of the older process has become much restricted, being at present confined to ores which, yielding freely to amalgamation, either are too low in grade to show an economic advantage in "all-sliming," or present chemical or other difficulties making the use of cyanide solution unadvisable during the crushing and preparation of the ore. South African ores are typical of the former class; Homestake ores are of both classes, but even in these instances the amalgamation work is being curtailed and greater burdens thrown on the cyanide plants. It is obvious that the time required for the dissolution of gold depends on the size of its particles. In an effort to determine the critical size, the following laboratory method was evolved. A standard amalgamation test2 had already been established, which involves the agitation of about 100 gm. of ore with 20 gm. of pure mercury, the latter then being separated and its gold contents determined. This method was applied directly to certain mill products with interesting results, a few of which may be noted here. The column "Free Gold" gives the value per ton thus amalgamated, as against the " Total Gold " determined by fire assay.

Jan 1, 1923

By Peter Heine

Diavik Diamond Mines Inc. (DDMI) has treated systems development as an integral part of the construction project when it built Canada?s second diamond mine. Fully aware that the proper collection and processing of operational data is needed to drive business decisions during production and planning, key Performance Indicators (KPIs) were defined to effectively manage operations when the mine went into production. The Production Information Management System (PIMS) allows KPIs to be measured, reported, and transferred to other systems in a reliable and convenient manner. PIMS provides a mechanism to collect real time production data from the various control systems around the site and acts as a tool to ?drill-down? and establish the important cause-effect relationships that impact the value of a KPI. Thus PIMS provides a data collection, storage, management, and an environment in which cause-effect relationships can be analysed and statistically verified. This understanding of the real cause-effect relationships, close to the source of the data and in the context of the operation, can be used to improve both operations and maintenance performance. The PIMS includes the PI Database implementation, its associated external interfaces with the various Control Systems, Cleaning Packaging Weighing System, Environmental System, Enterprise Asset Management (EAM) System, and Diamond Tracking System (DTS), as well as laboratory data collection, custom applications (downtime tracking, data reconciliation) and user clients. The interface with the EAM system provides material flow quantities and equipment availability on which the plant performance reports are based. The transfer of equipment usage to the EAM system is fed into the maintenance notifications and work orders functionality in the EAM. The environmental system interface provides the mechanism for capturing water consumption data required to generate the various regulatory reports. The interface to the cleaning-packaging-weighing system provides the mechanism for capturing batch data for transfer to the DTS for diamond product tracking at the production splitting facility in Yellowknife. The PIMS lab application provides a means of getting sample data into the system for critical metallurgical metrics, and the data reconciliation application provides a means of manually verifying the data before it is published or passed onto other systems.

May 1, 2003

By J. M. Ohm, C. M. Bunker

Two special tools for recovering gamma-ray probes and logging cable from drillholes have been designed by Ohm and Bunker and constructed by Ohm. Though intended specifically for U. S. Geological Survey equipment, they may be used with other equipment of the same general type. Fishing Tool for Probes: A fishing tool of the overshot type (Fig. 1) was designed to retrieve logging probes (sondes) that become disconnected from the logging cable and are trapped in the drillhole. When the tool slides over the top of the gamma-ray probe, studs on the bottom engage the shoulder near the top of the probe (Fig. 2), which is then pulled to surface. The barrel can be constructed from brass or steel tubing. Wall thickness is not a critical dimension, but the tool should be heavy enough to sink through mud or water in the drillhole. The internal length of the tool must be enough to prevent interference with the upper end of the probe head as the tool slides over it. The design of the probe head used by the USGS required a minimum free space of 2 1/2 in. inside the fishing tool, which was made 7 1/2 in. long to increase the weight. The lower end, which engages the shoulder of the upper end of the probe, contains three studs placed at 120" around the circumference of the tool and held in the engaging position by the tension of a spring wire. The studs can be made of any metal, such as steel, having high tensile strength. As the tool slides over the probe the studs are pushed outward from the center against the spring tension, allowing the tool to slide into position below the shoulder of the probe head. The spring tension forces the studs inward into the engaged position after they pass the shoulder. When the tool is raised the studs stop against the shoulder, preventing the tool from sliding up over the top of the probe. Once it engages the shoulder of the probe it cannot be freed until both probe and fishing equipment are recovered from the drillhole.

Jan 1, 1960

By S. J. Sindeband

J. WULFF*—It seems to me that the author could improve the quality of his high temperature material by using less nickel as a cementing agent in hot pressing. Furthermore, to avoid the presence of undilfused nickel which would not be oxidation resistant, permit me to suggest that he use a nickel-chromium powder containing a small percentage of boron. This would give him a liquid phase at a lower temperature and accelerate both sintering and homogenization. The commercial alloy known ascolrnonoy contains sufficient chromium to be heat resistant and sufficient boron to be of low melting point. Such an alloy may be applicable as a cementing agent in increasing the quality of Mr. Sindeband's alloys. Finally 1 believe the author unfair to himself in expecting a porous material to have properties equivalent to one of 100 pet density. S. J. SINDEBAND—Dr. Wulff's point is well taken. Early in the program we realized the fact that we were having difficulty with these low-melting alloys, and we had hoped, since the colmonoy alloys of which you speak are at the nickel-rich end of the diagram, that by going to the other end of the diagram (chromium boride-rich) we would not have this difficulty. Thus we tried to use very small percentages of binder; but for reasons which are not exactly apparent we found that when we did this it was necessary to raise the pressing temperature to a point which we were unable to attain. For all compositions which we tried using nickel, or for that matter any nickel iron or cobalt containing material as a binder, we found that we would get low melting boride phases, which as you point out are the commercial "strength" of the hard-facing materials. 1 personally believe these owe a great deal of their behavior and even hardness to the nickel boride which is considerable evidence when an alloy of chromium boride is made with nickel. Nickel boride itself is very hard. We did try pure chromium as a binder and found there was considerable difficulty in handling it, particularly since we could not just hot press under

Jan 1, 1950

F. JOHNSON,* Birmingham, England (written discussion t).--. Mr. Skowronski's first melting experiments tend to show that ingots with a "level set" may be obtained without oxygen. Now it is characteristic of all metals which occupy a smaller volume when solid than they do when molten to "pipe." In vertical-cast ingots, this pipe resembles a horn-shaped cavity, with the wide mouth uppermost. In horizontal-cast ingots, the pipe is a longitudinal furrow along the center-line of the ingot surface. If copper be successfully deoxidized and degasified, this furrow will inevitably be produced. In the author's oxygen-free ingots, it is. clear that gases were occluded and these gases effectively opposed the formation of a pipe or furrow by shrinkage (fluid contraction). It is riot a special property of any particular gas which produces this effect. Hence it is not surprising that the author has succeeded in producing level and overpoled ingots through the agency of sulphur. dioxide gas. That he has counteracted the overpoling influence of sulphur by means of oxygen is somewhat difficult to explain, since the well known reaction between cuprous sulphide and cuprous oxide should result in the production of sulphur dioxide gas. Why the presence of excess cuprous oxide should neutralize the overpoling influence of this gas without eliminating sulphur is not at all clear. It is to be regretted that the oxygen was not determined in the bars given in Tables 3 and 4. It is by no means established that sulphur is responsible for the over, poling of ingots given in Table 4, since carbon was used for overpoling. If, however, the same kind of poling treatment was given as that applied in the case of ingots in Table 1, the responsibility of sulphur assumes more definite shape. The author rightly points out that Mr. Johnson's theory of the equilibrium between gases and cuprous oxide does not explain why a simple addition of cuprous oxide does not correct an overpoled charge. Such a charge must be re-worked to "set" copper. This re-working (rabbling) undoubtedly forcibly removes the excess gases, which are not removable by cuprous oxide.

Jan 11, 1918

By Xiping Chen, Wangxing Li, Jiemi Zhou

"Desulfurization methods suitable for anode-grade petroleum coke (coke for short) used in primary aluminum industry are coke desulfurization during calcination, desulfurization in soakage and desulfurization in mediums. Coke desulfurization during calcination is discussed in this paper. Influences of calcination temperature, holding time and coke granularity on coke desulfurization were discussed. Experimental results show that calcination temperature has a remarkable influence on coke desulfurization. When the temperature is high enough desulfurization ratio of coke can reach 85% only by calcination. Holding time has a definite influence on coke desulfurization, but desulfurization ratio is low at the temperature of 900~1300°C. The influence of holding time is obvious when calcination temperature surpasses 1400°C. The influence of coke granularity is smaller compared with calcination temperature and holding time.IntroductionPetroleum coke is main raw material for carbon anode in primary aluminum industry, and its weight percentage in carbon anode is about seven percent. Green coke can not be directly used for anode production because of its immanent moisture and volatiles. Green coke must be calcined in order to meet the request of anode production. Calcination is a heat-treatment process during which green coke is heated to a given temperature to remove volatiles, moisture and some sulfur. Real density, strength, electrical conductivity and anti-oxidation ability of petroleum coke can be improved by calcination and calcined coke can be received [1, 3, 4]. Sulfur in calcined coke finally goes into carbon anode. During baking or aluminum smelting, the sulfur in anode ultimately changes into SO2 and emits from anode into the atmosphere. Excess SO2 easily leads to acid rain which brings heavy pollution to the environment [1, 2]. With the development of Chinese aluminum industry, consumption of anode-grade petroleum coke increases year by year, the total consumption in 2007 surpassed 4.5 million tones and the yearly emission of SO2 from aluminum smelters has exceeded 270 kilotones. From 2005 Chinese government began to limit the emission of SO2 from primary aluminum industry, so desulfurization of anode-grade petroleum coke becomes more and more urgent. Some relationship need to be found and used to guide desulfurization of petroleum coke."

Jan 1, 2008

By Victor C. Storhok, Batric Pesic, Marlyn D. Ballain

No1ihwest Alloys produces magnesium from dolomite by reduction with ferrosilicon and aluminum. This process produces alkaline by-products in quantities that allow their consideration for use as commercial products. Two such products are dicalci­um silicate, termed as Di-Cal, and magnesium oxide, termed simply MgO. The alkaline properties of these materials offer acid neutralizing power, comparable to traditionally used lime. Thus, the materials warrant study for their use in various appli­cations where neutralization of acidic waters or process solutions are required. One such application is the treatment of acid mine waters with the objective of removing heavy metals. The chem­ical stabilities of the produced metal precipitates are critically important, from an environmental point of view, for their safe disposal in tailing ponds. The EPA regulates waste material dis­posal according to the results from TCLP testing. In this ongoing study, three mine waters were selected for treatment with Di-Cal and MgO. Lime was used as the control for these experiments. The waters were collected from the Bunker Hill mine, Berkeley Pit, and the Blackbird Mine. In addi­tion to testing the chemical stability of produced metal precipi­tates by the TCLP procedure, two other parameters were studied as well. They are: 1. the effect of water pH on stability, and 2. the effect of pH on the stability of resulting precipitates. In the first three months of study, it was found that neutral­ization with Di-Cal results in precipitates that range from equiv­alent to superior in performance as compared to those produced using lime for the waters from all three mines. An additional beneficial characteristic of precipitation with Di-Cal is the fast filtering characteristics of produced precipitates, when compared to the precipitates produced by lime. This property may be of significance when considering the improvement in drainage of tailing ponds and the volume of solids produced. This paper will discuss in detail the stability of metal precipitates with respect to various pe1iinent metals found in mine waters of Berkeley Pit (Cu, Zn, Mn, etc.), Bunker Hill (Zn, Mn, Ni and Co), and Blackbird Mine (Cu, Co).

Jan 1, 1998

By Roy A. Hardy

The Getchell mine is a comparatively recent discovery in the old Potosi mining district, Humboldt County, Nevada, a district organized in the seventies and eighties, in which some prospecting was done in several metamorphic zones along a monzonite-sedimentary contact. The district had no production in the early days and no further work was done until the same metamorphic zones were prospected for tungsten (scheelite) in 1917 and 1918, when a few small lots were shipped. It again lay dormant until 1934, when prospectors investigated a large siliceous escarpment at one end of the old district where outcroppings were a prominent feature of the topography. Undoubtedly, during the early prospecting of the district, the outcroppings had been investigated for mineral, probably by panning, with negligible results because the gold later found is invisible in the concentrate and is refractory. A fire assay revealed the presence of sufficient gold to warrant development work. The outcroppings were easily prospected by short tunnels having their portals in the siliceous material on the hanging-wall side, with a maximum distance to crosscut to the footwall of 135 ft., or a distance at right angle to dip of 60 to 90 ft. Development work, reaching a depth of over 600 ft. on the dip of the vein, was done by means of various crosscut tunnels, winzes and laterals. A churn-drill hole was also sunk, which intersected. the vein at a depth of 1100 ft. on the dip. Sufficient development work of this character was completed by 1937 to justify the erection of a reduction plant to roast the sulphide ore and cyanide the calcine, and to treat the oxidized ore by straight cyanidation, to make a doré bullion for shipment to the mint. The erection of the plant was started that year and finished early in 1938; with a combined capacity of about 800 tons per day. It has operated continuously since erection and recently was enlarged to handle 1000 tons per day. The vein dips with the slope of the mountain, and by stripping the hanging wall the ore may be mined by power shovel for several hundred feet below the outcrop. Thereafter underground methods will be necessary.

Jan 1, 1941

By H. A. Gardner

THE principal use of barium sulphate is as an inert paint pigment.. For this purpose, the ground material is used both in its natural and in its artificial forms. Probably the largest amount is used in the production of a chemically precipitated pigment called lithopone which consists of 70 parts of barium sulphate and 30 parts of zinc sulphide. An enormous tonnage-of this pigment is at the present time being used in the manufacture of interior flat wall paints of the oil type, such paints having almost entirely supplanted the use of corroded white lead which was at one time used for interior painting. The more dense nature, lower price and sanitary value of lithopone was responsible for this change. Lithopone is, moreover, used to a large extent in the manufacture of oil cloth, shade cloth and linoleum. Its whiteness makes it of particular value for this purpose. Barium sulphate is also used of itself in admixture with other pigments in the manufacture of prepared paints. The chemically precipitated form of barium sulphate, which is generally called blanc fixe, is also used for this purpose. Much controversy has raged in the paint world over the question of inert pigments such as barytes, silica, asbestine and china clay. These pigments are probably called inert because they have no chemical action upon the linseed oil in which they are ground to produce paints, and on account of the fact that they become transparent in oil. It is well known that in the manufacture of paints, opaque white pigments, such as basic carbonate white lead, basic sulphate white lead, zinc oxide etc., are generally used as the grinding base. These base pigments, when ground in oil, react therewith to some slight extent, and they produce white paints which have excellent biding or obscuring value. The inert pigments so-called, when ground in oil and spread out into a thin film, form transparent coatings which have no hiding power. It has been contended, therefore, that the use of barytes or similar inert pigments in paints is resorted to simply for the purpose of cheapening the cost of the product.

Jan 9, 1914

By S. R. Elliott

THE principles of the caving system, as they apply to mining of soft iron-ore deposits, are well known, as this method has been in use for many years. It is, however, necessary to give a general description of it before describing the Athens method. The shaft and surface equipment should be placed at a sufficient distance from the orebody, so that the caving and pulling of the surface will not disturb the operations of the mine. Levels are started at the proper intervals, and when raises are completed, slicing commences at the top of the orebody and progresses downward. The necessary precautions are taken to avoid the occurrence of large open rooms and it is customary to break sufficient capping to form a mat to prevent heavy falls of ground from crushing through to the lower sublevels and endangering the lives of the workmen. Slicing is continued, and when sufficient width and length are undercut, the capping commences to cave, and in time a settlement occurs at the surface. As soon as this caving commences, the pressure on the timber naturally increases; after it extends to the surface, the amount of pressure has a certain relation to the depth. In other words, the pressure increases with the depth, but not in direct proportion. At great depths, such as that found at the Athens, 2500 ft. (760 m.), the pressure might be so excessive that the cost of keeping working places open would be prohibitive. The actual caving of the surface in a deep mine, with a great thickness of capping, is slow and often takes years to accomplish. After sufficient width and depth -have been undercut, the capping starts to break away, but through arching large masses of rock-.fill the opening, support the capping, and retard the continuation of caving. Caving to the surface is, therefore, retarded until either a sufficient thickness of the orebody is removed, or the width and length of the undercut part have been greatly increased. I wish to emphasize this fact of slow caving, for it is on, this principle that the success of the Athens system. largely depends.

Jan 8, 1920

F. WEIMER,* Washington, D. C. (written discussiont).-For electrical measuring instruments, especially those types that involve the Wheat-stone bridge or potentiometer principle and standards of electrical resist-ance, there has been, for a considerable time, a need for better resistance materials. For a satisfactory resistance material, much depends on the purposes for which it is to be used. For potentiometers and Wheatstone bridges, such as are in more or less general use, and the more common forms of resistance standards, a good quality of manganin answers fairly well. However, it should not be presumed that manganin is considered ideal for the purpose, for in measuring instruments and resistance stand-ards, there is still much to be desired. An experience of more than 10 years in the study of the resistance standards and resistance apparatus shows that manganin resistances change with time in a way that is very annoying and the maintenance of the unit of resistance to the desired accuracy requires an excessive amount of work or may be said to be prac-tically impossible. The changes in resistance are generally most rapid and erratic in resistances of very low and very high values. In resist-ances of low value, the resistance material is often in the form of thin sheets so that the surface is large and usually more or less unprotected from the atmosphere, or the oil in. the case of oil-immersed standards. In resistances of high value, the resistance material is in the form of fine wire and, therefore, the surface is large compared with the cross-section. In resistances of medium value, the surface is less, compared with the cross-section, or better protected, usually by a silk wrapping impregnated with shellac. This suggests that one of the difficulties with manganin is slow surface action or oxidation, even when an effort has been made to protect the surface from such action However, the changes observed cannot all be accounted for on this basis. There are, presumably, also some internal changes in the resistance material even when it has been annealed. Further; the changes in manganin resistances seem to be more or less independent of its electrical properties. In other respects, too, manganin is not ideal.

Jan 11, 1919

JOSEPH DANIELS, Seattle; Wash. (communication to the Secretary*). Mine models are of great value to the student and to the layman in visualizing underground conditions, and, in a measure, should be just as much a part of the equipment of a mining school as sets of ore specimens, catalogs, or drawings. The chief drawback, as Professor Stock has indicated, is the time and cost of making them. The greatest good in the development of the model comes to the person who makes it, and I have often wondered whether it might not be possible to have each student make one model during his undergraduate career. At the University of Washington we have been collecting sets of mine timbers, made of 6 by 6-in. lumber, illustrating shaft, level, and stope timbering. This work has been done by freshmen. Perhaps each educational institution could specialize in the creation of a certain type of model and exchange its product for that of another school, just as we now do with ore collections. In this way we could build up good museums at a relatively low cost. JOHN R. CHAMBERLIN, New York, N. Y. (communication to the Secretary?).-The type of model described by Professor Stoek is admirably suited to exhibits of coal mining in horizontal veins, and fulfills perfectly the three purposes mentioned. As an educational illustration in colleges, especially when the students themselves build the model under the direction of their instructors, it is of the highest value; and as each condition in mining requires special methods to depict properly in a model, the student is compelled to exercise considerable inventive resource to construct a true representation, stimulating the imagination and interest in his subject. Models built for exhibits in lawsuits are usually constructed to show prominently some particular feature of vein formation or geology, or the relation of underground workings to surface property lines, and as such their use is invaluable to the successful litigant. When the litigation is ended, it is natural that the model should be relegated to the basement and frequently destroyed, as data on underground workings are often considered of a private character by the operators; and it is

Jan 10, 1917