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A general review of grinding mill steel liner evolutions/developments in recent times. The driving force behind these developments has been the mill operators desire to minimise the nett cost of their operation. These developments have resulted from a team approach between supplier, operators and reline crews. The move towards larger diameter high aspect mills, faster mill speeds, pebble ports and the use of large diameter grinding media has affected the traditional liner designs, which is placing higher demands on the supplier to meet these new working parameters and expectations. Operators are also taking closer ownership in the liners being supplied, as demonstrated by the development of their own mill liner specifications. This paper outlines some of liner developments and changes undergone at various milling operations around Australia and overseas (such as Cadia Hill, Kidston, Ok Tedi Mining, PT Freeport, etc) and where to in the future?

Jan 1, 2000

By L. S. Urbanoski

This presentation describes a major modernization project at the Geco concentrator. The objectives of the program were to replace obsolete flotation equipment and upgrade process controls.Noranda Minerals Inc. — Gecc Division is located at Manitouwadge in Northern Ontario. The community is situated north of Lake Superior approximately equidistant from Thunder Bay and Sault Ste. Marie.Milling operations began in September, 1957. The mill processes a complex base metal ore by differential flotation techniques to produce copper, lead and zinc concentrates. To date some 43 million tons have been milled, qualifying Geco as a rather major base metal deposit.II. BACKGROUND:The Geco concentrator was designed and constructed in the mid 50's. A number of features specific to a concentrator of that vintage provided the justification for the modernization efforts described herein.Firstly, the mill was constructed without any instrumentation, not even pneumatic controls. Solid state electronics, computers and related instrumentation were unheard of, or rather primitive by today's standards.Secondly, some of the major equipment, in particular the flotation equipment, did not compare favourably to that in use today. MacIntosh flotation machines (more commonly known as Mac cells) were installed at Geco. These cells were prevalent in a number of concentrators built by Noranda, including Quemont Mining Corporation Limited, Gaspe Copper Mines Limited and Noranda — Horne Division. The Mac cells were used for copper and zinc rougher and scavenger operations. Some units were also installed for a pyrite recovery circuit that was never operated. In total, 104 Mac cells were installed in the main flotation area of the concentrator.

Jan 1, 1987

By P. R. Richardson

"Milling is the weak link in the process chain of many mineral operations. While this activity accounts for only a relatively small proportion of the direct costs of most mineral processing complexes, there are intangible and indirect costs associated with milling which are extremely large. For example, significant opportunity costs are associated with the relatively low yields which characterize this stage of the process.There are changes abroad in the world which I believe are going to cause us to reformulate the whole concept of milling. Increased competition in mineral markets are going to force managers to look anew at the high mineral values reporting to tailings which are a high opportunity cost for many operations. Tailings recovery plants are not the ultimate solution to this problem. Greater environmental concerns are going to increase the costs associated with tailings disposal and force the mining industry to look for other ways to dispose of waste products. Technology changes currently underway in manufacturing and other process industries, such as the automated 'lights-out' plant are going to be brought into this industry, and the changes will be dramatic.These are major long term changes which probably seem rather remote to many managers and professionals in existing operations which are faced with much more mundane challenges arising from day-to-day operations. However, I believe that milling is increasingly a 'lean and keen' operation involving fewer and fewer people, but who are increasingly skilled and professional. Traditional cost management approaches are no longer adequate and the industry has to take a new look at the nature of cost reduction in this core activity. This stage in the mineral process provides opportunities for value creation leading to a significant unit cost advantage for the corporations willing to adopt a total cost approach."

Jan 1, 1988

By Wheeler North

THE United Eastern Mining Co.'s property is located in the Oatman, Gold Roads mining district of Mohave County, Ariz. The mine and mill are some 26 mi. (41.8 km.) southwest of Kingman, the nearest railway connection. The ore consists of a mixture of calcite and quartz with some andesite. The values, which are mainly gold, alloyed with approximately 34 per cent., by weight, of silver, are extremely fine so that fine grinding is a most important factor in extraction. The milling process, briefly, consists of single-stage, coarse-crushing, two-stage ball milling in cyanide solution, followed by combined mechanical and air agitation, and by straight counter-current decantation. The Merrill zinc-dust precipitation method is used to recover the values, and is preceded by the Crowe vacuum treatment of the solution. The most notable features of the plant are the absence of filters, and the use of short peb mills loaded with steel balls, for fine grinding. As originally designed, the capacity of the mill was to be 200 tons per day, although the grinding end was to be capable of handling double that amount. By adding extra agitators and thickeners and by some alterations to the grinding end, the daily capacity has been raised to 285 tons. This, it is hoped, may be increased to 300 tons during the warm months of the present year. TONNAGE MILLED PER DAY 1917 average 234 Maximum month 272 Minimum month 146 1918 average 253 Maximum month 276 Minimum month 217 As this article primarily deals with plant operations, those interested in the mechanical description are referred to the article by Mr. Otto Wartenweiler,1 the designing engineer, which gives the details and costs of design and construction. The following changes have been made since that article was published:

Jan 8, 1919

By P D. Munro

On the occasion of the 14th Mill Operators’ Conference and marking 40 years since the first one was held in Mount Isa in 1978, it is fitting to review the history of the Conference and its development over that time.The first 10 Conferences were irregularly held at three to four year intervals, with 9 of these in regional centres of Australasia. It is only since 2012 that the Mill Operators’ Conference has become a regular biennial event, alternating with the MetPlant Conference.The number of people attending the Conference has more than doubled to 470 delegates at the 13th one in 2016. It has outgrown its regional beginnings.Papers presented to the previous Conferences have been analysed according to commodity, country of origin, technology and theme plus the affiliation of the authors to discern any trends that may assist in planning the future events.Suggestions are made as to how the AusIMM might wish to arrange its mineral processing/metallurgical conferences.Recent changes to the structure of the Conference providing a more meaningful experience for the delegates and increasing their interaction and involvement should be vigorously pursued.CITATION:Munro, P D, 2018. Mill Operators’ conferences – a 40-year retrospective and a vision for the future, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 5–14 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

By Steve Hubbard, Brad Marchant, Rolando Cuadra

"Triton Mining Corporation acquired the rights to Mina El Limon in Nicaragua in 1993 by international bid. The bid included the gold operations at Limon and an exploration concession of approximately 4000 km2. Triton assumed control of operations and exploration in May 1994.The Limon mine is located in west-central Nicaragua, approximately 100 kilometers northwest of Managua. The climate is tropical, characterized by a wet season from May through October, and a dry season November through April. Gold at Limon is associated with both banded quartz and silicified breccia veins in Tertiary volcanic rocks, belonging to the lower Coyol Group. Mining is from two open pits and one mechanized underground operation. A second underground mine is currently under development for production during 1997.This paper describes the expansion of the milling facility at El Limon from a nominal capacity of 400 tonnes/day, producing approximately 20,000 ounces of gold annually, to the existing 900 tonne per day mill operation. Engineering of the new mill facility was initiated in September 1994 and construction was completed a year later."

Jan 1, 1997

By P Rubie, B Morgan, J Russell, C Stewart

The relationship between efficient liner exchange, concentrator availability and concentrator profitability is well documented. Russell Mineral Equipment’s (RME) relationship with OZ Minerals’ Prominent Hill site personnel enabled sound collaboration between the two parties. Both parties worked together to identify the sources of productivity and efficiency loss and developed solutions to reverse them.This paper chronicles the identification of production inefficiencies and the resulting removal of mill relining from the critical path through the materialisation of mill relining optimisation strategies. Furthermore, this paper outlines other recent mill relining optimisation strategies developed by RME and tested at Prominent Hill, to demonstrate and achieve further productivity, efficiency and safety improvements.CITATION:Rubie, P, Russell, J, Morgan, B and Stewart, C, 2017. Mill relining optimisation – a story of collaboration, in Proceedings MetPlant 2017, pp 335–345 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 11, 2017

By V. K. Gupta

"Effect of mill speed on grinding kinetics has been investigated with a view to using mill speed as a manipulated variable for control and optimization of the grinding circuit performance under variable ore hardness conditions. Dry and wet batch grinding tests were carried out for quartz, limestone and cement clinker in a 29 cm x 18 cm laboratory ball mill. Mill speed values selected were 55 and 70% critical. In the case of dry grinding operation, with an exception of quartz, for all materials studied the effect of mill speed on grinding rate was found to be insignificant for sizes finer than about 35 mesh. In the case of wet operation, grinding rates were found to be approximately proportional to the mill speed. The implications of these results are discussed.INTRODUCTIONIt is well known that mill speed has a considerable effect on the grinding rate of the ore particles l-3 For particles of a given size there is an optimum speed at which mill grinding efficiency is maximum (i.e. specific energy consumption is minimum) 3•4. Mill speed can, therefore, be effectively used as a manipulated variable to deal with the disturbances arising from changes in the size and hardness (grinding rate) of the ore being fed to the grinding circuit. Though, it has not been the case so far, with recent developments of ring motors2 and frequency inverters5 a continuous variation of mill speed has now become feasible, and it is expected that mill speed control will soon be a regular feature of plant operation2,6."

Jan 1, 1985

By The Mill Staff

Introduction The Hollinger cyanidation mill commenced operating in June, 1912, and 49,779,978 tons of solids had been discarded by the end of 1950. The present tailing disposal plant has been in operation since 1924 and holds 39,762,250 tons. The tailing disposal plant is on the property of Kayorum Gold Mines, Limited, about a mile and a quarter south of the mill. The area available for tailing covers 640 acres and is roughly l ¼ miles long by ¾ mile wide. Tailing was first deposited on the McKay veteran claims, l mile long by 1/2 mile wide, which were later included in the Kayorum property. This site sloped from northeast to southwest, the slope amounting to 106 feet between the northeast corner and the low land to the southwest. The low land was wet and a considerable area was covered with muskeg up to 17 feet deep. It was drained by a brook running across the property in a southwesterly direction. Later, when more ground was needed, the low-lying mining claims adjacent to the south and west boundaries were acquired to allow for the extension of the plant. This entailed some extra difficulties and expense that would not have been encountered had the whole of the present site been acquired with the original purchase. At the present time, the top of the tailing deposit stands at two elevations, but eventually the tailing deposited on the extension to the original plant will be raised to the same height as the older deposit. Previous to 1924, all of the tailing was deposited on Low land and in lakes near the mil1. Between 1924 and 1926 an increasing tonnage was sent to the McKay claims until, in 1926, all of it was being sent there. In 1936, the area of the deposit was extended and shortly afterwards all of the tailing was deposited on the new site.

Jan 1, 1951

The Millennium deposit, located in northern Saskatchewan between the McArthur River mine and the Key Lake mill, has considerable potential for becoming an operating mine. Located in the Athabasca Basin, Millennium is blessed with both the riches and the challenges that this basin offers. The potential for ground water inflows during shaft sinking, and the unconventional challenges associated with underground uranium mining, render the successful development of a new mine in this area especially rewarding. The preliminary design and engineering of the Millennium Project has tapped into the experience of other operations in the area, and has utilized new applications of geophysics technology to enhance the understanding of the local geological structure. This discussion will focus on the innovations, and the challenges specific to uranium mining, for a deposit that is poised to be one of the next mines to supplement Saskatchewan's uranium resources.

May 1, 2008

By F. D. Ford, Z. Dai

"Vale’s Ontario Operations re-introduced Cu/Ni separation at Clarabelle Mill in 2006. The mill processes ores from a number of mines in the Sudbury basin. A saleable Cu concentrate is produced at 30-60% Cu recovery from mill feed, which has to meet the quality specification. In particular, Ni content in Cu concentrate must be less than 0.6%, otherwise, penalties will apply and diminish the value of Cu concentrate, in addition to the lost Ni value. Generally, a Ni grade of less than 0.4% is obtained in Cu concentrate. More recently, while processing Cu-rich ore, Cu concentrate contained more than 0.6% Ni which is abnormally high. Detailed mineralogical investigation shows that Cu-rich ore contains more millerite in comparison to typical Sudbury Ni sulphide ore. Millerite is found to be more floatable than pentlandite and is much more difficult to depress using high-lime aeration conditioning, which is the standard practice in Cu/Ni separation to float chalcopyrite while depressing pentlandite. The current operation uses sodium cyanide at 20 g/t to depress pentlandite and pyrrhotite. However, it is found that a high dosage is required to depress millerite. It is also shown that starch and dextrin are promising in millerite depression.INTRODUCTIONPrior to bulk smelting in 1991, Cu/Ni separation was carried out at Vale’s Copper Cliff Mill, Ontario Operation. The typical Cu concentrate grade was around 30% Cu and 1% Ni. This is very high in comparison to today’s value of 0.4% Ni and would not be acceptable for external processing. However, the Cu concentrate was processed internally at the Copper Cliff smelter/refinery, so the Ni contained in Cu concentrate was not lost and no actual penalties applied. During the SO2 abatement initiative, bulk smelting was chosen because of the perceived simplicity and consequently, Cu/Ni separation was eliminated (Agar, 1991) and the Copper Cliff mill was subsequently demolished. In 2005 and after more than one decade of bulk smelting, business changes required the removal of some Cu concentrate from Clarabelle Mill bulk concentrate to provide smelter capacity for Voisey’s Bay concentrate in the Copper Cliff smelter. In essence, this strategy calls for Cu removal at Clarabelle Mill (Lawson, 2006). In this case, Cu concentrate is sold externally and it must meet the quality requirement of less than 0.6% Ni."

Jan 1, 2011

By N Robb

This paper gives an account of the laboratory testing, plant testing and final inclusion of the two-stage sulphuric acid leaching process in the Milliken mill. Operational results for September, 1962, are presented, showing a uranium extraction of 95.5 per cent, with a saving of some 16 lbs. of 100 per cent H~S04 and some 9 lbs. of lime per ton milled. Methods for effecting further improvements in the process are indicated. HISTORY P RIOR to the incorporation of two-stage leaching, the process for the treatment of uranium ores at Milliken consisted of a single-stage sulphuric acid leach, followed by a solution recovery step involving washing in thickeners and two-stage filtration. The thickener overflow solution was subsequently concentrated and purified by ion exchange, and the uranium was recovered, by two-stage precipitation, as ammonium diuranate. Figure I illustrates this flowsheet. For satisfactory extraction of uranium from the. Milliken ore, a high residual acidity, of the order of 40 grams per litre of free acid in the discharge solution, must be

Jan 1, 1963

By C S. Stevens

This paper describes the problems encountered and the steps taken to solve them in milling an ore containing relatively large amounts of pyrrhotite. A complex and greatly lengthened flotation circuit was required to recover the pyrrhotite. A very low pH had to be maintained in the cyanide circuit in order to get good recovery of the gold and maintain reasonable cyanide recovery. Introduction D ELNITE Mines Ltd., a gold mine situated about 5 miles by road south and east of the town of Timmins, Ontario, is serviced by two shafts. No. 2 shaft extends from surface to the 2875-ft. level, and No. 3 shaft, an internal winze, extends from the 2875-to the 5275-ft. level. No. 2 shaft was stopped at the 2875-ft. level because of a heavy band of chloritic schist which necessitated a drive to the north for 1000 feet, where No. 3 shaft was sunk. The latter bottomed in the schist at the 5275-ft. level. From the 2500 to the 2875-ft. level in No. 2 shaft, the ore was

Jan 1, 1965

By Charles E. Locke

SHARP CONTRAST exists in the reports so helpfully contributed by the individual members of the Milling Committee for this review. Those engaged in the milling of gold and silver ores report great activity, of which some details will be given later. Those engaged in milling ores of base metals report continued depression and little progress. Copper production in the United States is running at about fifteen per cent of capacity. Some Arizona copper mills are closed. Anaconda is milling about 45.000 tons of copper ore per month, and the Utah Copper Co. 35,000 monthly. However, in Canada the International and Falconhridge copper-nickel mills and the Noranda copper-gold mill have increased production. Also the Climax molybdenum mill in Colorado is milling 4000 tons per day. Water shortage from the drought has caused curtailment or complete shutdown of mills in some parts of the West.

Jan 1, 1935

By Wm. C. Madge, H. P. Allen

The chloridizing mill of the Standard Reduction Co. is located about 75 miles south of Salt Lake City on the Tintic branch of the Denver & Rio Grande Western R. R. and 12 miles from the Tintic Standard mine. The daily capacity is 200 toss of a siliceous, low-grade, silver-lead ore from this property. It has operated continuously since it was started in January, 1921. The process consists essentially of a chloridizing roast followed by a percolating leach with a nearly saturated solution of common salt, acidified with sulfuric acid, the precipitation of silver on sponge copper and of copper and lead on tin-plate cuttings. The precipitates are shipped to a smelter. Some of the general ideas involved are said to have been used by Augustin in England, in 1840. A number of textbooks treat of the subject, especially the chloridizing roast followed by a leach with sodium hyposulfite or amalgamation. The process was revived in this district by Theo. P. Holt, N. C. Christensen, the Bureau of Mines, and others. Nature of Ore Treated The average assay of the ore treated during 1924 is as follows: Gold, ounces per ton...................................... 0.025 Silver, ounces per ton..................................... 18.26 Copper, per cent......................................... 0.30 Lead, per cent........................................... 5.00 Silica, per cent........................................... 65.00 Iron, per cent............................................ 10.00 Lime, per cent........................................... 0.70 Sulfur, per cent.......................................... 3.00 Arsenic, per cent......................................... 0.70 The silver is finely disseminated and occurs as native, combined as a sulfide and, to a very small extent, as the chloride. The lead may be present as carbonate, sulfide, or sulfate.

Jan 1, 1926

By J. P. Dick

THIS paper is a description of the milling practice and metallurgy at the Moneta Porcupine mine, Timmins, Ontario. The results obtained with an all-cyanide circuit and later with flotation followed by cyanidation are described. The ?investigation which prompted the various changes in milling practice have also been dealt with. Moneta ore is possibly the most refractory now being milled in the Porcupine district. This is due to the ultra fine state in which the gold occurs and to its intimate association with pyrite. No doubt there is ore of similar characteristics on the neighbouring properties but it probably forms only a small portion of the tonnage being mined, whereas at Moneta the bulk of the ore requires an extremely fine grind to liberate the gold. The fineness to which an ore can be ground economically has gone far beyond what was thought to be the limit only a few years ago. Formerly, a set of standard screens was all that was required to measure the fineness to which an ore was ground. At present, the Haultain infrasizer is practically indispensable, and the nominal micron has become a familiar unit of measurement to all those dealing with the problems of fine grinding.

Jan 1, 1941

By Owen Matthews

THE property of Cochenour Willans Gold Mines, Limited, is in Dome township, Red Lake area, northwestern Ontario, a hundred miles north of Kenora and close to the Manitoba border. 'Planes of Canadian Pacific Air Lines, Limited, serve the district daily, except Sundays, from Kenora, Ontario, and Lac du Bonnet, Manitoba, passengers being trans-ported from Winnipeg to Lac du Bonnet by car. Freight is handled by the Patricia Transportation Company. It is brought in from Hudson, Ontario, on the Canadian National railway, in summer by water and in winter by tractor trains over the frozen lakes. The first staking on the property was done during the 'rush' of 1926 and 1927 by William M. Cochenour, and on April 30th, 1928, a syndicate was formed, taking in claims of W. M. Cochenour and Dan Willans and H. G. Young. Surface trenching was carried on almost continuously until 1934. In October, 1932, Ventures Limited took an option on the property, and in December of that year they carried out an extensive diamond drilling programme, but considering the results did not justify further work, they relinquished the option. In July, 1934, further surface work was carried out under the supervision of W. P. Mackle and, on the strength of his report, Noah Timmins Incorporated took an option on the property and agreed to make an initial expenditure of $100,000 on development work. This was carried out under the direction of Hollinger Consolidated Gold Mines and included the sinking of a shaft to a depth of 165 feet, establishment of a level at the 150-foot horizon, and some 1,900 lineal feet of drifting and cross-cutting. The results obtained from this work were not considered of sufficient promise and the option was terminated in August, 1935. Mr. Cochenour then approached Alex Mackenzie and associates, and the present Company, Cochenour Willans Gold Mines, Limited, was organized on April 9th, 1936, and sufficient money was raised to continue operations. Under the direction of W. P. Mackle, the shaft was deepened and a second level was established at the 275-foot horizon; but, due to several adverse reports by outside engineers, it was found impossible to raise sufficient money to carry on the work and operations were suspended in December, 1937. In January, 1939, an agreement was entered into with Gold Eagle Gold Mines for the milling in their plant of some Cochenour ore. A total of 4,959 tons was treated, and the results were so encouraging that further finances were raised by C. A. Gentles & Company, of Toronto. Following further development in the mine, it was decided to erect a mill. Construction was started on September 1st and the mill was turned over on November 29th. The first gold brick was poured on December 23rd.

Jan 1, 1942

IN presenting a'description of milling and treatment methods at the Waihi mine, it is advisable to first traverse a good deal of the past history of the mine, and show the various steps which have led up to present-day practice. The record of the company is one of steady, solid advancement, both in metallurgical and financial results. This is illustrated by the following figures, dating back from 1897...

Jan 1, 1912

By K. Mikulash

"Agnico-Eagle Mines Limited is located at Joutel in North-Western Québec. The mine is about four miles north-west from the town on the left bank of the Harricana River. The present mining is 1,800 feet deep with an extensive geological development below this level.HISTORY The development of the ore body started sometimes in 1967 and then the operation ceased in 1969 and again reopened in 1973 due to higher prices of gold. During these periods of active development, a considerable metallurgical research has been done by different laboratories and research and design companies.The original capacities of the Mill differed as much as 30%. So did the concept of the ore treatment. The original design of the mill was for 200 TPD of ore with straight cyanidation. The problems with low gold extraction, high reagent consumption and poor filtration resulted in a decrease of the expected mill output to an initial 550 TPD with gold recoveries in the order of 40 to 60%.Although the studies and research work done on the ore varied, all of them had a common conclusion: a very fine grind is needed to expose gold. The mining method (sub-level blast hole mining) now provides the ore that differs from that on which the metallurgical test work was conducted and the original capacity calculations had been done.These variations in the concept consequently led to the conclusion that the size of gold is a determining factor for the process.Kilborn Engineering provided the original design with the Leslie Eng¬ineering completing the design. The metallurgical test work has been done by the Department of Energy, Mines & Resources, Lakefield Research of Canada, Kilborn Engineering and Sidam Incorporated.The new flotation section with secondary grinding has been designed and put into operation by the company in December 1975 with the results yet to be evaluated."

Jan 1, 1976

By Harry J. Cain

Introduction The property of Pioneer Gold Mines of B. C., Limited, is located in the Lillooet mining district of British Columbia, on Cadwallader creek, 54 miles distant by motor road from Shalalth, a station on the Pacific Great Eastern railway. Milling by the present Company was commenced in 1924, a small amalgamation plant, consisting of a crusher, Bryan mill, and plates being operated until 1928. Tailing from this plant was impounded and later treated in the 100-ton continuous counter-current decantation cyanide plant which was erected during 1927-28 and placed in operation during May of 1928. A second cyanide plant, employing continuous counter-current decantation, having a nominal capacity of 200 tons, has been erected during the past few months and was put into operation during September of the present year. The ultimate capacity of the combined units of the present mill has not been determined, but it is expected to be much in excess of the rated capacity. The Ore The ore, as received at the mill, consists chiefly of quartz carrying free gold, with small amounts of pyrite, arsenopyrite, and pyrrhotite in evidence, though probably amounting to less than one per cent of the total. Some gold is very closely associated with the sulphides. The country rock is a basic igneous rock, probably an augite diorite. Near the vein it is highly altered to sericite, which slimes readily on grinding, and does not settle very well. The quartz is of two types, clear and ribbon. In the latter, the ribbons, which are not much thicker than paper, consist of shattered sulphides. In crushing this ribbon quartz, breakage is often along the streaks, exposing these shattered faces to advantage in subsequent treatment. While gold is the metal for which the ore is mined, some silver is also present and is paid for by the mint. It is, however, unimportant from a commercial viewpoint. From the standpoint of crushing and grinding, the ore might be termed 'medium 'hard'.

Jan 1, 1932