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By M. M. O?Brien

THE SULLIVAN MINE The Sullivan mine of the Consolidated Mining and ? Smelting Company of Canada, Limited, is situated at Kimberley, B.C., nineteen miles from Cranbrook, a divisional point on the Crowsnest Pass branch of the Canadian Pacific railway. Production started on a small scale in 1900, and in 1914 the mine became the largest lead producer in Canada. In 1925 it was the largest single producer of lead and zinc in the world. Since operations commenced, 4,800,000 tons of ore have been produced from stopes and 170,000 tons from development. At the present time, ore is being mined at the rate of 1,100,000 tons per year, with a yield of about 200,000 lb. lead, 110,000 lb. zinc, and 4,000,000 oz. silver. The town of Kimberley is easily accessible by road as well as by rail. The altitude at Mark creek, a tributary of the St. Mary's river, is 3,700 feet. To th'e north of the creek, Sullivan hill rises to a height of 6,100 feet, and it is on the southern slope of this hill that the mine is located. Sullivan hill is in the Purcell range, which rises between the Rocky Mountain trench on the east and Kootenay lake on the west. It thus lies within what is commonly referred to as the East Kootenay district.

Jan 1, 1926

By Mario Bergeron

L'exploration géologique pour les EOP (EOP: platine, palladium, iridium, osmium, ruthénium, rhodium) requiert avant tout des méthodes appropriees à la mesure de ces élémenIs. L'approche analytique choisie doit tenir compte de plusieurs facteurs, les plus importants étant: le type de materiel analysé, sa representativite, la sensibitite de la methode et les cotits reliés à son utilisation. Dans cette optique, plusieurs démarches ana/ytiquessont possibles, toutes requérant une étape de préconcentration. L 'une des plus adéquate consiste à effectuer une préconcentration par fusion plombeuse suivie d'une analyse par émission au plasma, cette procédure permettant de mesurer Ie platine, la palladium et Ie rhodium à des couts compétitifs (15 $/échantillon). Advenant 10 presence de teneurs appréciables de l'un ou plusieurs de ces éléments, une préconcentration par fusion au sulfure de nickel suivie d 'une analyse par activation neutronique assure alors la mesure de tous les EGP ainsi que celie de l’or (90 $/échantillon). Il est important de noter que Ie nickel, ades teneurs superieures à 4%, interfère au cours de l'étape de préconcentration par fusion plombeuse, ce qui se traduit pas sous-dosage des concentrations en platine, effectivement presentes dans l'échantillon. Ainsi, les géologues à la recherche d'EPG dans des environnements géologiques riches en nickel devraient s'assurer que l'analyse utilise, au cours de l'étape de préconcentration, une fusion au sulfure de nickel.

Jan 1, 1990

By T. Schepp, T. Friedrich

"The natural stage of deep mines operation is a closure of unnecessary shafts. It is extremely important to ensure a proper shaft closure to avoid stability loss and the associated damage to surface facilities in the future. For the still active shafts, it can be done by a dedicated shaft closure design, but even then, depending on the shaft closure method, it may be necessary to perform regular shaft inspections. The paper presents a short overview of shaft closure methods and available tools and devices developed in the last time for such shaft inspections. INTRODUCTION The natural stage of deep mines operation, commonly occurring after depletion of the reserves of mined materials, is a closure of unnecessary shafts. All over the world, the number of liquidated shafts grows continuously and the problem of shafts disposal is especially critical for deep shafts. The typical depth of 600 m of currently liquidated shafts in Poland may already be seen as a challenging task. The greater is the challenge of shaft closure in Germany where the last active coal mines for shafts with a depth of up to 1,300 m have been recently closed. It is therefore extremely important to ensure a proper shaft closure to avoid stability loss and the associated damage to surface facilities in the future. For the still active shafts, it can be done by a dedicated shaft closure design, but even then, depending on the shaft closure method, it may be necessary to perform regular shaft inspections. In many cases, it is more important to inspect old, abandoned shafts, where the wall stability or even liner type are not fully known. SHAFT CLOSURE METHODS Abandoning a shaft is a complicated task, as shafts, being the link between the surface and an underground network of workings, disturb hydrogeological and gaseous conditions in the rock mass (Sztelak, 1991). Closure procedures at older mine sites have been carried out in accordance with earlier legislative requirements. For very old shafts (+100 years), it means in many cases only a sealing of the shaft entrances by means of timber or concrete slabs. In the 20th century, the shafts were also closed by means of filling with grainy materials, but even then the retrospective activities at abandoned mine sites were extremely limited and in most cases no further monitoring measures were performed. The possible consequence of an improper shaft closure and lack of monitoring is presented in Figure 1."

Jan 1, 2019

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

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

Jan 1, 2014

By Pizhi Zhao, Jingwei Zhao, Zhenshan Liu, Yiheng Cao

"A new Al-Mg-Si-Zn alloy designed for automotive outer panel was trial-produced with industrial procedure. The final product shows a strong planar anisotropy. X ray diffraction analysis shows such strong anisotropy is caused by the dominating cube texture component in the final product. The reason for such high cube texture component was investigated by tracing texture evolution starting from the hot roll slab. It is found that certain cube texture components already exists in the hot rolled slab. The density of cube texture component shows as a wavy change through the following1st cold rolling, inter-annealing, 2ndcold rolling and solution treatment. This study shows that the cold rolling in the laboratory can well represent the texture evolution during the industrial production. The results obtained by lab rolling hints that change of second cold rolling reduction has weak effect on the planar anisotropy, when the gauge of hot rolled slab and final sheet are fixed.INTRODUCTIONWith the rapid progress of light-weighting in the automotive industry, aluminum sheets get more and more application as closure panel and structure parts. Recently the dominating alloy for outer panel is 6xxx series, containing the main alloy elements Mg and Si. The popular gradesareAA6016,AA6111, AA6022, and AA6014. These alloys still cannot satisfy the various requirements from automotive manufacturers. Most suppliers of automotive aluminum sheets are developing their own specific grades according to the customer’s demand. To increase the baking response, anew Al-Mg-Si-Zn alloy was designed, concerning the high combination energy between Zn solutes and vacancies formed during the quenching stage of automotive sheet manufacture. This combination is helpful to the precipitation of ß”phase during the paint baking (Wang, 2015,2016; Yan, 2014).The plastic strain ratio (r value)is a key index of the formability of automotive body sheet. A high r value means a good formability. The r values in different directions can be used to evaluate the planar anisotropy of the metal sheets. The trial produced Al-Mg-Si-Zn sheet shows a strong planar anisotropy with respect to r values. Since the r value is tightly related with texture, the texture evolution from hot roll slab (HRS) to final T4P temper was analyzed with X ray diffraction (XRD) to find the reason for the high anisotropy. Besides, the cold rolling reduction (CRR) was varied in the laboratory to modify the texture distribution, i.e., the planar anisotropy."

Jan 1, 2018

By T. Avilez, D. Salari

"The economics of developing gold deposits containing elevated levels of cyanide soluble base metals is often challenged by high cyanide consumption and increased operating costs. SART is a chemical process that enables cyanide consumed by base metals to be recovered and recycled for gold leaching. The process also provides concurrent recovery of the base metal to generate incremental revenue from the sale of high-grade base metal sulphide concentrates. Although SART was developed and successfully piloted by Lakefield Research and Teck Corporation in the late 90’s and is now a public domain technology, the adoption of SART has been relatively slow due to concerns about implementation costs and the reliability of metallurgical performance. Through extensive experience in selective metal sulphide precipitation applied to mining wastewater since 2007, BQE Water has provided process know-how, design along with operations and maintenance experience to a number of projects involving the integration of SART into various metallurgical flowsheets on an industrial scale. This paper presents the commissioning experience and operating data from a SART plant treating up to 500 m3/hr of leach solution at a heap leach operation in Mexico. INTRODUCTION One of the current trends in the gold industry globally is the increasing importance of complex polymetallic gold deposits as discoveries of large Carlin type gold deposits become increasingly rare (Sceresini, 2005). The presence of cyanide soluble copper and zinc in complex gold deposits necessitates changes to the traditional gold extraction metallurgical flowsheet. A tool available to the industry to help manage the interference of cyanide-soluble base metals in gold extraction is the SART (sulphidization-acidification-recycling-thickening) process. SART breaks the weak acid dissociable (WAD) base metal-cyanide complexes, precipitates the metals as high-grade sulphide concentrates and makes the freed cyanide available for recycle."

Jan 1, 2018

By V. W. Shtenko, B. J. Ennis, P. H. Bridge

"The northeastern region of British Columbia contains large quantities of high-quality metallurgical coal. To market the coal, it was necessary to provide the required infrastructure which included rail access. This paper presents the role of the British Columbia Railway in the northeast coal development.In 1976, B.C. Railway undertook to study two main routes, one originating at Chetwynd and the other at Anzac, both located on the main line, north of Prince George. The routes studied are briefly described, detailing the methodology and engineering analysis carried out to permit the selection of a single route that would be the most cost effective, taking into consideration the construction, maintenance and operating costs. The operating parameters, track and grade standards, anticipated tonnage, construction costs and the final route selected are also presented.Pre-engineering analysis and studies of the route selected originating at Anzac, known as Tumbler Ridge Branch Line, and which commenced in 1977, were concluded in 1978. New mapping was developed to a scale of 1:2000 with good vertical and horizontal control. Based on the mapping data, terrain analysis, and designs developed, an estimate of construction costs and schedule of work was developed.Authority to proceed with the final design and construction was provided in December 1980, with the first shipment scheduled for December I, 1983. Final designs of all structures are discussed, including schedules, cost to completion, and control systems utilized. The decision to electrify the Tumbler Ridge Branch Line and related topics are discussed, with a brief description of train operations. The present status of the project is also presented."

Jan 1, 1983

By P. R. Clark, M. D. Gleghorn

"IntroductionAt TransAlta Utilities Corporation's Highvale Mine, located west of Edmonton, Alberta (Fig. I and 2), dragline stripping has proved to be a practical and economical method of overburden removal and future plans have been based upon the continued use of draglines (Fig. 3) as the major stripping equipment (Williams, 1979, Nikols et al., 1986). However, long range planning has shown that the capacity of draglines alone will be exceeded in the early 1990s as mining progresses into deeper overburden cover (Tapics, 1983). Strip ratios will increase from I.3 bank m!/ t of coal in 1985to 4.5 bank m3 / t in 1995. During this period the depth of overburden will increase substantially and the areas to be mined will be characterized by weak soils including glacially displaced overburden. This increased overburden depth in relatively weak soils will make it impractical to _continue side casting by draglines without prestripping in advance. In 1983, a major investigation was initiated to determine what additional overburden removal equipment was appropriate to the Highvale operations, and recognizing the long delivery times of this major equipment. when it would be required. This paper describes studies and tests which were undertaken in 1983 and 1984 to select prestripping methods and equipment for the future operation of the mine.Previous planning studies have shown that with the current burn schedule and with the economies of progressing from low cover to high cover, as has been practiced in the past, overburden volumes will exceed the capacity of the existing draglines in the early 1990s (Fig. 4). These previous studies had placed reliance on (I tandem dragline operation for future overburden removal requirements up to a depth of 45 m throughout the Highvale Mine. New drilling together with the associated geotechnical studies and some detailed planning on the practicality of using tandem draglines, created concerns about their universal application. Even without considering geotechnical conditions there was a depth limitation to tandem dragJines and substantial prestripping would be required to achieve the ultimate depths."

Jan 1, 1987

By Derek E. McBride

"Exploration work in the Beardmore - Tashota area has led to a reinterpretation of relationships between gold mineralization and the geologicalevolution ofthe area. The host volcanic rocks form two parallel volcanic belts connected by a much smaller cross-cutting band, which trends northeast from Beardmore to Tashota. This connecting band consists of mafic and felsic volcanic, plus clastic sedimentary rocks in a sequence conformable with the contact of the Onaman Lake Batholith to the east. A metamorphic aureole or incorporated xenoliths are lacking along this major contact and the only intrusive relationship observed is chilling between mafic dikes and a cold host granite in proximity to it. Granite dikes are totally lacking in the volcanic succession, or the overlying sedimentary sequence. A major part of this sequence consists of a polymict basal conglomerate with granite boulders and volcanic clasts in a fine-grained chloritic matrix. The nearest source for these boulders is the Onaman Lake batholith.Gold mineralization in significant economic quantities (+ 50 000 ounces) occurs at the top or above the mafic volcanic succession as quartz bands. In the Northern Empire Mine, the band is conformable, folded, boudinaged and the mineral zoning shows a relationship to variations in the host rock, not structural overprinting. In general, where the host mafic tuff is medium-grained, the quartz band is thicker, up to a metre wide, and carries economic grade; where the tuff is finer-grained and bedded, the band is very thin and low grade.Stratigraphic control and metal zoning shows that the mineralization formed as part of the development of the volcano- sedimentary succession. The other major deposits in the area (Leitch and Sturgeon River) have a similar structural history suggesting that they are also syngenetic in terms of the stratigraphic development. Regionally, these deposits were emplaced prior to any significant tectonic deformation but at the end of the mafic volcanic event.The mafic activity was related 10 a period ofextension which caused the volcanic troughs to develop along centres of rifting. The hiatus at the end of this event permitted extensive hydrothermal systems to form and deposit siliceous exhalite bands within sedimentary or terminal mafic volcanic environments in promixity to major thermal sources. Subsequently, the Kenoran Orogeny deformed the entire succession into upright folds with a sub-vertical schistosity. Evidence shows that the deposits have remained intact since deposition."

Jan 1, 1987

By The Staff

WE were requested to make a digest of our original grinding report, Fine Grinding Investigations at Lake Shore Mines. This digest is much easier to read than the original report, but it lacks the experimental 'evidence' found in the first report which, in many cases, is much more interesting and educational than the conclusions derived from it. In the course of rewriting the paper, we noticed several new angles on the test data which had not occurred to us previously. From the data included in the report and other tests not published, calculations were made which indicated a line of new test work. These tests, among other things, more than suggest a technique for designing the length of mills, the position and number of classifiers, and the total loads a mill should carry.

Jan 1, 1941

By G. C. Hambleton

"The author has had wide experience in the reclamation of coal from coal mine waste dumps in the United Kingdom.The paper includes such topics as the processing decision and factors affecting processability; method of testing and appraisal; test data interpretation; historical influences in apppraisal; special contaminants and processing difficulties; methods of treatment; review of systems in use and their comparative economics; over-all system economics including excavation, handling methods, recovery system and shale disposal; effluent treatment; environmental considerations; alternatives to processing for coal recovery; light aggregate and cement usage; burned shale heaps; land reclamation; shale deposition for encouragement of vegetation by natural or artificial means; use of tailings fines; the environmental argument for action."

Jan 1, 1972

By B. R. Conard

Occupational epidemiology of the nickel-producing industry has found that inhalation exposures to certain nickel-containing substances are linked to respiratory cancers and to nonmalignant respiratory endpoints. Establishing such a linkage, however, is complicated by the fact that some diseases occur long after exposure to a causal agent (i.e., some diseases have long latencies). Furthermore, most chemical agents (especially nickel substances) vary significantly in their toxicological properties and their concentrations in workplace air have varied over processing history. Because of these complications, it is critical to understand historical exposures to specific nickel substances. To assist in this effort, the author focuses on the history of smelting and its related processes at Vale Canada’s (Inco’s) Ontario operations in the first half of the 20th century.

Jan 1, 2012

By R. H. Knudsen

"In view of the chronic overcapacity problem in the world potash industry and Saskatchewan's recent emergence as a major producer, the long-term outlook for potash productive capacity and consumption is of importance and interest to both the Saskatchewan Government and the potash industry. This paper is based on a report recently published by the Saskatchewan Department of Mineral Resources on projected world potash productive capacity and consumption for the ten-year period 1970 to 1980. Potash productive capacity and consumption are estimated on a country and regional basis and projected annually to 1980. Tables and graphs are included which summarize projected capacity and consumption for the period and illustrate the impact of Saskatchewan's capacity upon the North American and world potash industries."

Jan 1, 1973

By M. Board, R. Pakalnis, S. Seldon, R. Brummer

The Kidd operation mines roughly 10 000 tpd of copper and zinc ore from underground and employs about 700 personnel. In the late summer and fall of 1997, major movements in the proximity of the east wall of the Kidd open pit had been observed. The Kidd pit had been mined from 1965 to 1977 to depths of 260 m (850 ft), followed by subsequent mining by underground methods to current depths in excess of 1830 m (6800 ft). The No. 1 Mine (2600 Level to pit bottom) is approximately 90% extracted, with most of the remaining reserve between 2000 and 2500 levels. Although initial concerns centred on the stability of the pit walls, the potential ramifications of the movements to the underground were recognized and measures were implemented to ensure the safety of personnel as well as to minimize the potential damage to existing operations. In late October, damage to underground operations was observed as deep as the 2000 Level. In the final assessment, the global mobilized mass was a “wedge”-shaped hangingwall block extending from surface to about 610 m (2000 ft) below surface. The “wedge” boundaries are defined by a fault and shear zone which have continuous lengths in excess of 1070 m (3500 ft); its base by shearing through the host rock mass; and its eastern face by deep tension cracks (Fig. 1). Mined and filled excavations at the western face of the “wedge” allowed mobilization of a mass in excess of 30 M tonnes. Movements in excess of 75 cm (30 in.) per day were recorded on the surface stations that preceded the complete shutdown of operations on October 29, 1997. The evaluations in the days following the shut-down were centred on mitigation of immediate and future possible negative impacts on infrastructure and mining of the remaining No. 1 Mine reserves while ensuring the safety of the operators. This effort required the rapid assessment of the potential damage of the block movement on underground infrastructure, stope access, drainage and ventilation, as well as airblast potential due to the falling of a large block into the pit near the ventilation intake at the base of the pit. These assessments were presented in a previous paper (Seldon et al., 1999). In total, the lateral movement of the block on the ground surface was over 4.3 m (14 ft). This paper describes the detailed studies performed to understand the failure mechanism and to assess the impacts on future mining in No. 1 Mine.

Jan 1, 2000

By John A. C. Fortescue

There is a need for better communication between scientists who plan and carry out mineral exploration research in glacial terrain and the exploration geologists who look for mines. In this paper, four ways in which workshops could be used to close this communication gap are described and discussed in relation to the solution of this problem in Canada.

Jan 1, 1973

By B. Jin

Removal of fluoride and chloride by alkaline washing from direct lead smelting dust which originated from an Ausmelt furnace is reported. The results show that the fluoride removal efficiency increases with an increase of alkaline concentration, alkaline washing temperature and time. The L/S ratio has little effect on fluoride and chloride removal efficiency. A new flow sheet for removal of fluoride and chloride from the dust was successfully proposed according to the results. Fluoride and chloride removal efficiencies are more than 53.68% and 63.18% respectively using the flow sheet under the optimum parameters of temperature 338 K, L/S ratio 3:1 and alkaline washing time of 1.5 h. The contents of fluoride and chloride in the alkaline washing residues can meet the standard of zinc purity as hydrometallurgical materials for zinc processing.

Jan 1, 2014

By C. R. van Staal, L. R. Fyffe, J. A. Winchester

"The geochemical characteristics of Early Paleozoic volcanic rocks are used to establish the following tectono-volcanic regimes in the northeastern mainland Appalachians: foreland continental rift volcanics; fore-arc ophiolites; island-arc volcanics; back-arc ophiolites; and back-arc ensialic volcanics. A Late Precambrian calc-alkaline magmatic arc bounds the Early Paleozoic volcanics to the southeast.The Precambrian calc-alkaline volcanics of the Caledonian Highlands, primitive Cambro-Ordovician oceanic-arc volcanics of the Eastern Townships, and within-plate Ordovician volcanics of the Miramichi Highlands can be related to a progressive change in mode of subduction from compressional Andean-type in the Late Proterozoic to extensional Western Pacific-type in the Early Paleozoic. The development of marginal oceanic basins in the Paleozoic created a more favourable environment for volcanogenic sulphide deposition, particularly in back-arc areas.The influence of tectonic setting is reflected in the distribution, size and metal ratios of the massive sulphide deposits associated with the volcanic rocks; deposits within intra-oceanic arcs in the Eastern Townships of Quebec average two million tonnes grading 2.2% Cu, 4.0% Zn, and 0.6% Pb, whereas those within a back-arc, ensialic rift near Bathurst, New Brunswick, average nine million tonnes grading 0.6% Cu, 5.4% Zn, and 2.2% Pb."

Jan 1, 1990

By Tong Guan, Guangqin Fu, Lihong Deng, Yuanlin Chen, Xiaotong Zhou

"In natural world, some kinds of scheelite minerals are rich in molybdenum. Molybdenum exists in the crystal lattice of scheelite in the form of isomorphism, and the content of MoO3 varies from 2% to 10%. As a result, the flotability of seyrigite (scheelite with molybdenum) turns to be weaker. One seyrigite mine, which has been built for 3 years,still could not produce qualified seyrigite concentrate due to the weak flotability of seyrigite (Mo-bearing scheelite) in raw ore. In our experimental research, through adopting new seyrigite collector TA-3 and advanced mineral processing technology, the seyrigite concentrate with a grade of 65.62% WO3 at a recovery of 87.47% was obtained for the raw ore containing 0.19% WO3 and 0.074% Mo. By applying the new technical achievement, for the raw ore containing 0.272% WO3, the seyrigite concentrate assaying 68.03% WO3 with a recovery of 77.56% was obtained in industrial production.INTRODUCTIONIn natural world, some kinds of scheelite minerals are rich in molybdenum. Molybdenum exists in the crystal lattice of scheelite in the form of isomorphism, and the scheelite is changed to be seyrigite (Ca[(W,Mo)O4]) (Ma, Bian, & Wang, 2013). The content of MoO3 in seyrigite varies from 2% to 10% usually, the content of MoO3 in some of the seyrigite even reaches 34%. The flotability of seyrigite is weak (Zhang, 2007), and the seyrigite is difficult to be recovered by flotation with common collectors and regulators. One scheelite mine in Anhui China, which is a skarn type seyrigite mine, has not produced qualified concentrate yet since 3 years it has been built due to the limit of beneficiation technology. Therefore, it is necessary to conduct research on the collectors with high efficiency and developing advanced processing flow for this kind of ore."

Jan 1, 2016

By A. Holland, T. Krumins, E. Olin, J. F. M. Castilleja, J. Geldart, C. Fleming, I. Jackman

A flowsheet has been developed to treat the flotation tailings from a copper mine in Mexico to recover gold and silver by cyanidation and carbon-in-pulp (CIP). The plant will treat ~15,000 t/day of a 60:40 blend of current flotation tailings and the mine’s historic tailings. The tailings also contain a significant amount of cyanide-soluble copper, and the economic viability of the project is strengthened by recovering most of the copper and cyanide associated with this process. The solution and solid phases in the CIP tailings will be separated in a counter current decantation (CCD) circuit and the CCD solution overflow will be treated by a SART Process. Copper precipitates as a salable copper sulphide product in the SART Process and the cyanide that is associated with the copper complex is regenerated as free cyanide. After SART, a portion of the SART product solution will be recycled to leach to reuse the free cyanide, while the remaining solution will be used as wash water in the CCD circuit. Incorporation of the SART Process in the flowsheet allows the CIP circuit to be operated aggressively as a gold plant, which means most of the silver in solution passes through CIP to SART. Silver co-precipitates with copper in SART and is recovered very efficiently with the copper sulphide by-product. Incorporation of SART also allows the leach and CIP circuits to be operated with relatively high levels of free cyanide, which enhances silver leach kinetics and helps keep copper from loading onto the carbon in CIP. The flowsheet was developed in the laboratory and successfully demonstrated in a fully-integrated pilot plant in 2018.

Jan 1, 2019

By A. E. Flynn

THERE is at the present time a revived interest in amalgamation, due to the number of mines starting up, usually on high-grade ore, and utilizing this relatively cheap and convenient means of recovering gold, more especially in their initial stages of production. The marked increased use of the amalgamation process has revealed a dearth of amalgamators and there is no doubt the art of amalgamation has stood still for a generation or two and is not readily applicable to the modern practice of milling gold ores. Mill operators of long experience are learning the art for the first time and are giving it intelligent study, and considerable testing and research work is now being undertaken Most millmen consider amalgamation a simple process, and so it is when we have a clean ore with coarse gold, specially when stamps are used for crushing. In treating Nova Scotia ores by stamps and amalgamation, recoveries of 95 to 97 per cent are common and easily obtained. So-called 'under-water feed' is almost universally used in Nova Scotia and is quite beneficial. The water is supplied through jets between the dies and below the die surface and maintains this space as a live trap which catches the gold particles before they are overground and spoilt for amalgamation. With this method, the portion of gold recovered in the battery is higher than usual and often amounts to 80 per cent of the total gold in the ore, the remaining 20 per cent being caught on the plate. As a continuous amalgamator, the simple plate cannot be excelled. Some of the modern devices having moving or covered and not very accessible plates, which cannot be readily inspected and dressed to keep them in condition, do not give the best results in service. An exception might be drawn in the case of amalgamation of very heavy ore or concentrate which would bank up unless the plate is carried at such a steep inclination as to weep mercury. Difficulties in stamp-mill amalgamation are encountered when acid water is used or when grease is present. Also, certain sulphides and graphitic and talcose ores give trouble, resulting in poor gold recovery and high mer-cury loss. The older literature on gold milling deals with the common troubles of this type and the old-time amalgamator was well able to take care of day-by-day difficulties. When the difficulties were unsurmountable, the ore was classed as 'refractory' and other processes were used.

Jan 1, 1939