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By D Marshall

The sub-level blasthole benching method of mining has been proved to be economical at Willroy Mines. How-ever due to the nature and attitude of the wall rock, this method is susceptible to serious hanging-wall dilution of the ore. Attempts to solve the dilution problem by various means were not satisfactory until long Stressteel bars were employed as rock bolts. The adoption of this de-vice does not require any special skill, and has become routine in the under-ground operation. Since the inception of this method, the dilution of the ore has been greatly reduced and the ov1!r-all costs of controlling this dilution are much lower. INTRODUCTION T HIS is a report describing the successful use of long Stressteel bars as rock bolts in preventing l1anging-wall failure and consequent dilution in open stopes. Willroy Mines Limited is located (Figure 1) near the town of Manitouwadge, Ontario, approximately l1alf-way between Sault Ste. Marie and Port Arthur.

Jan 1, 1963

By Stanley Davidson

Introduction The ore deposit mined by Falconbridge Nickel Mines, Limited, is one of the numerous nickel-copper sulphide bodies marginal to the large oyster-shaped mass of differentiated norite in the Sudbury district, famous as the world's most important nickel producing field. The unique character of the ore deposits of the district has resulted in its intensive geological study over a period of more than fifty years. The results of these studies have given rise to a voluminous geological literature and to a great deal of controversy as to the genesis of the ores. This description of the structural geology at the Falconbridge mine is presented in the hope that it may form a small part of the chain of evidence leading to a reasonably satisfactory explanation of the ore genesis. The mine, named after Falconbridge township in which the deposit occurs, lies along the southeast margin of the norite mass which, however, is here concealed beneath a deep mantle of glacial sands and gravels averaging over 100 feet in thickness. As a consequence, the deposit was not discovered by the early prospectors, and it was not until 1916-17 that E. J. Longyear, of Minneapolis, located the ore by drilling. The discovery was foreshadowed in 1899 by the work of Thomas A. Edison, who found indications of the deposit by what is believed to have been a combination of magnetic and electrical geophysical surveys. He sank a prospect shaft over what has to date proven to be the largest and richest ore section in the mine. A wet quicksand layer at the rock surface proved impenetrable, however, and the "Edison' shaft never reached bed-rock.

Jan 1, 1946

By Y. Hayashi, A. Fuwa

To analyze zinc vaporization kinetics of zinc smelting slag in the ISP furnace, reduction reaction rate of zinc oxide from ZnO-FeOx-CaO-SiO2 slag system with CO-CO2-Ar gas mixtures has been measured by a therm o-gravim etric apparatus at various ZnO content, Pco, and temperature. The reduction rate was measured under a chemical reaction control in the initial three minutes where surface zinc content can be assumed constant. Through the reaction rate dependency analysis on ZnO contents, Pco and temperature, discussion has been made on its reaction mechanistic information in terms of rate coefficient, adsorption/desorption mechanism and activation energy.

Jan 1, 2008

By C. H. Stockwell

"The Precambrian rocks of southeastern Manitoba contain a great variety of mineral deposits, including gold, chromium, copper, nickel, lithium, tin, beryllium, tungsten, and molybdenum. Although considerable interest has been shown from time to time in each of these types of deposit, production to date has been almost entirely in gold. This has had a value of about $26,000,000 and has been derived chiefly from the San Antonio mine, with lesser amounts from the Central Manitoba, Gunnar, Beresford Lake, Ogama-Rockland, Diana, and other properties.Most of the deposits lie within volcanic and sedimentary rocks or within basic intrusions cutting these rocks. These favourable rocks occur in several areas, which have been given local names and are separated from one another by large bodies of granite (Fig. 1).In general, the several areas are characterized by different types of mineralization. Thus, the Rice Lake-Beresford Lake area contains numerous gold deposits and has yielded almost all the gold production to date; the Maskwa River, Euclid Lake, and Oiseau River areas are, on the whole, characterized by deposits of chromium, copper, nickel, lithium, tin, and beryllium; and in the West Hawk Lake area there are deposits of gold, tungsten, molybdenum, and lithium.As might be expected in a district containing such a variety of mineral deposits, the structural conditions controlling their deposition also vary greatly. It is, accordingly, convenient to discuss the structural geology and mineral deposits of each of the more important areas separately."

Jan 1, 1954

By J. E. Hawley

"The property of Francoeur Gold Mines, Limited, lies directly west of the Armfield mine in Beauchastel township, Abitibi district, and 12 miles west and slightly south of Noranda. The gold deposits are of particular interest because of their replacement character and close association with fault zones. The property was originally staked in 1923 following the discovery oi a mineralized zone near the eastern boundary. This became No. 1 orebody. Later discoveries in 1936 of No. 2 and No. 3 orebodies led to underground development and actual mining in July, 1938. A fourth orebody, No. 8, was found in 1939.The following is the production record up to December 31st, 1947:Beginning in September, 1944, ore was shipped to Noranda as siliceous flux, but late in 1946 milling of low-silica ore from No. 1 orebody was undertaken until operations were temporarily suspended in 1947.The four main ore deposits, Nos. 1, 2, 3, and 8, consist of siliceous ferrocarbonate and albite replacement bodies mineralized with fine pyrite and specularite in schistose fault zones in Keewatin volcanics. Barren to low grade quartz veins though present in some are uncommon, but small stringers of quartz are usually present wherever here and there visible gold is found. Nos. 1, 2, and 3 deposits lie in a major fault zone that extends completely across the property from west to east (over 7,000 feet) and dips N.40° to 50°, and are separated by intervals of 1,800 to 2,000 feet respectively. The fourth lies in a smaller fault zone striking east and dipping on the average 65°S.No. 1 orebody has been explored by mining to a depth of 500 feet, No. 2 to 400 feet, and No. 3 to slightly less than 300 feet . The greater part of No. 8 lies above a depth of 200 feet, but a raise has recently .been driven through from the west end of the 5th level of No. 1 to the 2nd level on No. 8 zone. Most of the ore of No. 8 zone above the 2nd level and of Nos. 2 and 3 above the 3rd levels has been removed."

Jan 1, 1954

By Louis Frost

"A FIRE which forced the sealing -of the east side of Dominion No. 16 Colliery in the Town of New Waterford, Nova Scotia, occurred on October 6th, 1952 (Figure 1).So far as can be ascertained, the fire was first noticed in the roof of No. 7 East Lateral, after a brushing shot had been fired in the pavement. There appears to .be no doubt that this shot •blew out, igniting a small feeder in the roof.Regular air measurements and air samples, taken over a long period prior to the fire, indicated that the ventilation was adequate, for at no time had the percentage of CH4 in the general air current exceeded one per cent in this location. The last regular monthly samples and air measurements, taken at the end of September, showed the condition of the ventilation to be:Return at the Top of No. 8 East WallQuantity .... 27,700 cu. ft. per min.CH4 .......................... 0.32 per centC02 ................................ 0.10 per centHowever, in the week preceding the fire the mine examiner on four occasions had reported small feeders of gas at the face of the brushing in No. 7 East Lateral.Figure 2 is a diagram of the working place where the shots were fired. The face brushing had been shot down at 3 :45 p.m. and cleaned up. Two 'hurdle screens' had also been erected, one close to the face brushing and the other fifteen feet from the face."

Jan 1, 1953

By E. F. Evoy

"The Gunnar uranium deposit was within metasedimentary rocks of the late Archaen Tazin Group. These rocks were intensely altered by albitization so that the immediate host to the ore consisted dominantly of albite, and by the subsequent introduction of calcite. The ore consisted of disseminated pitchblende and uranophane in a pipe-shaped breccia zone. Oxidation of the ore was more intense near surface than at depth, but there was no near-surface enrichment.IntroductionThe Gunnar Mine site is on the tip of Crackingstone Peninsula, on the north shore of Lake Athabasca, Province of Saskatchewan, Canada. The peninsula forms the southern part of the Beaverlodge mining area. The ore consisted of disseminated pitchblende and uranophane in brecciated metasedimentary rocks of the Tazin Group, and the deposit was characterized by extreme albitization and subsequent carbonatization of the host environment.Production from the mine began in 1954 and the ore was depleted by 1963. In that interval the deposit yielded about 5 million tonnes of ore containing about I. 75 kg/tonne U3O8. It was mined initially from an open-pit and subsequently from underground; the open-pit contributed about 55% of total tonnage. Uranium was recovered by atmospheric leaching in sulphuric acid, ion exchange concentration, and precipitation with magnesia.This paper is based on studies made during the productive life of the mine and is concerned primarily with pre-ore alteration of the rocks containing the deposit, and with the ore mineralogy."

Jan 1, 1986

By James W. Cassie

The Snap Lake Diamond Project is located approximately 220 km northeast of Yellowknife, NT, Canada at an approximate latitude of 63?35?. The project location is within the zone of continuous permafrost; measured ground temperatures are about ?2?C at 10 to 20 m depth below surface. The site is located on a peninsula jutting into Snap Lake. The site is generally barren of vegetation, except for some isolated areas with low trees located in topographic lows and near the shoreline of Snap Lake. As part of phased evaluation process with regards to the mining project, an Advanced Exploration Program was undertaken in 2000 and 2001. This program included the underground extraction of a bulk sample of kimberlite, which was processed on site. A Processed Kimberlite Containment (PKC) area was required as part of this program. The area chosen as the PKC facility was a small inland lake, called Inland Lake #1, on the peninsula. Construction of the PKC area required the construction of two dams, one on either end of the lake. At the south end of the lake, Dam 1 was constructed partially on a talik and partially on continuous permafrost. Dam 2 was constructed entirely on permafrost. The effects of the remote location, selection of suitable construction materials and permafrost conditions on the designs of the dams are discussed. A description of the design elements and construction schedule are provided. A review of the performance of these two dams, in terms of settlement, deformations, pore pressures and thermal regime, over the last several years is provided.

May 1, 2003

By J. Starkey

A comminution circuit in recent history, is one of the most difficult parts of a mineral processing plant to design with confidence. It is usually the most costly part of a plant to build, and it can consume up to half or more of the energy used on a mine site. To suggest that comminution energy usage is sustainable in the long term is not possible at this time. What we have to choose from today, based on more than 50 years of experience, does include the best available technology, and the best way to design it. There is controversy in the industry as to how to properly approach the subject of comminution design, with many of the optional solutions requiring a level of training and expertise beyond the ability of a non-specialist engineer. Semi-autogenous grinding technology in particular, has not been properly appreciated because of many recent mistakes in its application and design, which have blurred the positive perception about what SAG technology is, how it can be used, and how it needs to be designed and built. In order to change this, mine owners and senior managers need to take responsibility for, and learn to understand the fundamental challenges that a comminution circuit poses to the project, to the design process, to the operators who use the equipment, and to the resulting metallurgy. This address is intended to summarize these challenges and offer fundamental engineering solutions, which are clear, specific and in a format which is directly applicable to the mining and mineral engineering community.

Jan 1, 2018

By S. A. Sadough vanini

In this paper, Stress-Strain-Temperature relations for Shape Memory Alloys are studied. Temperature effects on Shape Memory Alloys are different from those related to ordinary materials. In ordinary materials, elastic characteristics can be assumed to be constant in low temperature ranges, and only the deflection arising from temperature changes could be added to the elastic defection. As long as two phases of austenite and martensite could be present in Shape Memory Alloys simultaneously, elastic modulus follows temperature and temperature gradient. In continue a smart actuator is investigated considering a homogeneous cantilever beam. Beam bending is established by using shape memory wires. An initial strain is imposed to shape memory wires in a low temperature, and then, they are installed in the outer surface of the beam. Therefore, since the temperature is imposed in these wires and they cannot have free recovery strain, the compressive recovery stress will be produced in the outer surface. This will result in a deflection in axial direction of the beam. At first, beam deflection is calculated on the basis of theoretical relations and solving the relevant differential equations. Afterwards, experimental tests are performed on an elastomeric beam equipped with shape memory wires. When a voltage is applied, a temperature rise will occur in the wires; then, this temperature rise causes a deflection in the beam. Finally, the theoretical and experimental results? comparison indicates a good conformity. One capability of this actuator is its high flexibility, and by controlling the inlet current, the end-beam deflection can be controlled.

Oct 1, 2011

By Walter K. (Cory) Conrad

Two pumping tests in the Chilson Member of the lower Lakota Formation were completed at nearly the same location in 1979 and 2008. The 1979 test consisted of a pumping well and several surrounding observation wells penetrating the full 55-m thickness of the aquifer. The 2008 test consisted of a pumping well and three surrounding observation wells screened over 10 m in one of the known uranium ore horizons in the lower portion of the Lakota penetrated only about 3 meters of the more than 55-m thick lower Lakota aquifer. The average transmissivity and storativity values determined from the 1979 tests were 17.6 m2/day and 1.8 x 10-4, respectively. Comparing median transmissivity of 13.9 m2/day and storativity of 1.2 x 10-4 determined in the 2008 test to the 1979 test, the new aquifer parameters for the lower Lakota are respectively about 80 and 70 percent of the 1979 results. Because transmissivity and storativity depend on aquifer thickness, comparing the results suggests that there may be some scaling effect between the tests due to the differing lengths of screened intervals. However, the effect cannot be predicted by calculations such as relative screen lengths or open intervals to the formation, or sandstone versus shale thicknesses on geophysical logs. The scaling effect is attributed to partial disconnection between the lower and upper portions of the Lakota Formation aquifer by locally continuous shale interbeds. Suggestions to resolve this scaling issue are presented.

Aug 1, 2010

By G. D. Ruttan

"LYNN LAKE, in northern Manitoba, has become Canada's second nickel-producing area. The discovery by Sherritt Gordon Mines of nickel ore in an entirely new district was the result of systematic prospecting of a belt of volcanics and sediments situated 100 to 150 miles north of the Company's former copper-zinc mine at Sherridon, Manitoba.Prospecting in this area was begun in 1937 and continued each year until 1941, when Austin McVeigh, a company prospector, found a patch of sulphides on a gabbro outcrop near a small lake named Lynn Lake. Samples from this sulphide indicated nickel and copper in significant amount. In 1943, magnetometer work disclosed a number of weak anomalies in low ground near the discovery. In 1945, staking was followed by geophysical surveys and diamond drilling, which continued through 1947. During this period the A, B, E, EL, and Corebodies were located and partly outlined. The discovery of the high-grade ""EL"" orebody in January 1947 was the turning point in the estabishment of the mine. Subsequent development, including additional exploration on surface and under-ground, evolution of a new metallurgical process, financing, erection of a mining and milling plant, hydro-electric power development, building of a rail line from Sherridon (by Canadian National Railways) and a refinery at Fort Saskatchewan, Alberta, culminated in August 1954, when the first shipment of nickel left the refinery. This paper, presented at the 1955 Annual General Meeting of the C.l.M. in Toronto, was one of a symposium covering the whole operation."

Jan 1, 1949

By A. D. Mufch, G. P. Mitchell

"THE HARDY MINE of Falconbridge Nickel Mines Limited is located in Lot 9, Concession 1, Levack Township, Sudbury District, Ontario, 20 miles northwest of the city of Sudbury, and a mile west of the town of Levack. The ore deposit is one of the many nickel-copper sulphide bodies found on, or near, the lower contact of the well-known Sudbury norite-micropegmatite irruptive, and is one of a family of ore deposits which occur on the northwest rim of the irruptive.The property was acquired by purchase in 1935. In the same year a magnetometer survey along the footwall contact of the norite, which is covered by about 150 feet of glacial sands and clays, first indicated the location of the orebody. Drilling from 1935 to 1942 outlined the extent of the ore. Shaft sinking was commenced in the fall of 1951, and the mine is now approaching full production at a rate of about 300,000 tons per year.There are several major differences between the geology of the Levack area and the Falcon bridge area, which lies at the opposite extremity of the irruptive, 28 miles to the east. The purpose of this paper is to describe the essential features of the geology of the Levack area as seen in the Hardy mine, and to supplement the recent papers on other properties in the Sudbury area by Davidson (1), Lochhead (2), and Yates (3).General GeologyA recent review of the regional geology and an extensive bibliography of the Sudbury area can be found in the two papers by H. C. Cooke (4, 5). Some of the recent related references are: Jas. E. Thomson (6), E. M. Abraham (7), Franc. R. Joubin (8), W. G. Q. Johnstone (9)."

Jan 1, 1949

"The Waite-Amulet, an important copper-zinc mine, lies astride the Duprat-Dufresnoy township boundary about 8 miles northwest of Noranda, Quebec. It is an amalgamation of two properties, that of the former WaiteAckerman- Montgomery Mines to the north and that of Amulet Mines, Limited, to the south. This amalgamation took place in 1933. The description that follows is confined to the Amulet section.Ore was first discovered on the Amulet property in the autumn of 1924. The C Shaft and Upper A orebodies were found in 1925 and the F orebody in 1929, the latter by diamond drilling under a swamp. Under the present management, Lower A ore body was discovered by diamond drilling at a depth of 700 to 1,200 feet in 1938, and new ore was found from the old C Shaft workings between 1943 and 1945.From April 15th to October 20th, 1930, 60,291 tons of ore was produced from the Amulet. During the second half of this period, the ore averaged 4.2 per cent copper, 16.3 per cent zinc, and 0.02 oz. gold and 3.35 oz. silver per ton. Due to the prevailing low prices of metals, there was no further production until July, 1937. Output was greatly accelerated in 1940 when the newly found Lower A orebody assumed the main burden of production. Up to January 1st, 1946, mill reports indicate the treatment of the following ore: GENERAL GEOLOGYFig. 1 shows the geology of the entire property. To the east is the Lake Dufault granodiorite stock and to the west the Flavrian Lake granite mass. Around the granodiorite and separating the Waite from: the Amulet section is an older diorite intrusion. The ore occurs in a series of lavas that form a broad anticline pitching eastward at a relatively low angle into the Lake Dufault intrusives. There are several steep east-west faults. The late Powell diabase dyke is shown, also the general areas of strong dalmatianite alteration, a type closely associated with the sulphide mineralization."

Jan 1, 1954

By Helen Francis

Over the last decade, lower ore grades and deeper mine environments have demanded that mining companies develop new technologies (tools and processes) to ensure a mine?s economic sustainability. At Inco Ltd., this demand has lead to the focus of technological development within the area of automation. Delineation (Drilling and Interpretation) is a key step in the determination of ore grade and location and therefore was chosen as a priority area for enhancement through automation. Focusing on the tools (the diamond drill) automation, significant benefits have been consistently achieved in terms of productivity, process efficiency, operational safety, cost reduction, component life cycles and machine reliability. It is suggested that optimum benefits have yet to be achieved, and will not be achieved until the human aspects of automation have been properly addressed. Since project inception, the human aspects of automation were recognized as critical to the success of the diamond drill automation project. However, it was only upon the installation of the Automated Diamond Drill in the field and its continued use on a daily basis that this issue received due attention. The human aspects of automation can be broadly addressed as economic, physical and psychological. This paper, with examples from the field, will discuss the human aspects of automation in each of these areas. The paper will draw from observations and experiences acquired throughout this project and recommend implementation strategies that should be utilized in future automation projects to enhance both the acceptance of automation and the success of the automated process itself.

May 1, 2002

The Buzwagi Project is owned by Barrick Gold Corporation and located in the Lake Victoria Goldfields of central Tanzania in the District of Kahama in the Region of Shinyanga. The property is 6 km Southeast of the town of Kahama, 3 km South and adjacent to the road between Nzega and Burundi. The Buzwagi property is 97 km South of Barrick?s Bulyanhulu Mine. There is access to the rail line which connects from Isaka to the Indian Ocean coastal ports of Dares Salaam and Tanga. The Feasibility Study and permitting were started in early 2006. Project Execution commenced in August 2007. Process Plant commissioning started in January 2009 and the first gold pour is scheduled for Q2 2009. The reserve has been established as 3.3M oz of gold plus 177M lbs of copper. The project has been developed to include a 30Mtpa Open Pit Mine and 4.4 Mtpa Process Plant. Over an expected 15 year mine life, Buzwagi is anticipated to produce approximately 3.02M oz of gold and 220,000 tonnes of copper concentrate. Infrastructure associated with the project includes a 107 km 220kV power line, site accommodation, water harvest and extensive security facilities. The project is expected to be built on budget and on time during a period of extreme market volatility. This paper reviews the initiatives taken to achieve community support, control cost escalation, maintain schedule and manage logistic challenges, plus ensure security and safety of all workers.

May 1, 2009

By Percy Coulter

"GeneralThe Malartic Gold Fields mill is presently treating ore from four different companies. The ore is delivered by truck, by the shipper, and dumped into the Malartic Gold Fields ore bin. This ore varies in size from 'Run of mine' to minus 8 11, All ore is crushed to pass a 3/ 8 11 x 4 11 cross slotted screen.Weighing and SamplingAfter crushing the ore passes over an adequate-weigher (250 T .P.H. capacity) on its way to the fine ore bins. This weigher has a remote counter at the sampling point.A 36” Vezin sampler cuts 15% from the ore stream as it enters the mill bins. This portion is elevated, by means of a short belt conveyor, to feed the No. 2 Vezin sampler. (This elevation is necessary to give headroom for the following machines). The ore on the conveyor is levelled to give a uniform stream to the second sample cutter. The second, third and fourth cutters are 2411 •The No. 2 Vezin sampler cuts 19% from its feed and this portion falls directly into a 1611 x 1011 Denver rolls crusher. This crusher reduces the ore to -1/ 8 11 , approximately. The discharge from the rolls crusher falls on a revolving circular plate with scraper, which gives a uniform stream to the No. 3 Vezin sampler.The No. 3 Vezin cuts 10% from its feed. This portion falls on another revolving plate to give a uniform stream to feed No. 4 Vezin."

Jan 1, 1966

By Fabian Mohr

The methyl substituted binuclear cyclometallated gold(I) complexes [Au2(?-n-MeC6H3PPh2)2] [n = 4, 5 and 6] all undergo oxidative addition reactions with halogens and, in the case of the 4- and 5-methyl substituted analogues, with dibenzoyl peroxide to give metal-metal bonded digold(II) complexes [Au2X2(?-C6H3-n-MePPh2)2]. The 4- and 5-methyl substituted digold(II) compounds on warming or exposure to light undergo carbon-carbon coupling reactions to give gold(I) complexes containing the corresponding 2,2'-n,n'-biphenylyldiphenylphosphines. The 6- methyl substituted digold(II) complexes rapidly isomerise above ca. -20° C to binuclear heterovalent gold(I)/gold(III) compounds [XAu(?-2-Ph2PC6H3-6-Me)AuX{?2-(6-MeC6H3-2-PPh2)}], containing a fourmembered cyclometallated ring on a gold(III) centre. Surprisingly, no carbon-carbon coupling could be induced for any of the 6-methyl substituted compounds, even under forcing conditions. This difference in reactivity of the 6- methyl derivative, compared to that of the 5-methyl and unsubstituted analogues was studied by ab initio calculations using a series of model compounds. The results are in excellent agreement with the experimental findings and suggest that the key-step in the C-C coupling reaction is the partial opening of the Au(III)-P bond in one of the transition states. In the 6-methyl system this transition state is energetically inaccessible and hence no C-C coupling occurs.

Oct 1, 2003

By J. W. Keyes

"The original grinding circuit at East Malartic consisted of two 8 by 8 C.A.C. mills in closed circuit with two 72 inch Akins Classifiers and an 8 by 10 secondary mill in closed circuit with two 48 inch duplex classifiers. With this circuit, we experienced a drastic drop in tonnage from one month to another, due to variations in the hardness of the ore. The first step to overcome this difficulty was made by increasing the critical speeds of the mills from 78% to 82%. This resulted in an increase in the secondary mill throughput; but, when the change was made on the primary mills no increase was obtained.The drastic drops in tonnage were still experienced and through working with Allis Chalmers the 8 by 10 mill was converted to a rod mill and the two 8 by 8 n1ills to secondary mills. This change eliminated the two 72 inch Atkins classifiers and the scoops on all the mills, since the 48 inch Akins classifiers sands could then be fed by gravity to the secondary mills through feed pipes.The rod mill and secondary mill discharges were fed to a common pump box using 5 by 5 S.R.L.'s running at 1085 R.P.M. with a twenty-five foot head. When this was done the pumping costs jumped from $105. 00 for 6 months to $1050. 00 in one month, or from 0. 0004 to 2. 75 cents a ton milled. Several factors contributed to this jump in pumping costs as follows:"

Jan 1, 1964

"In mills, metallurgical efficiency is important in every step of the operation through to the tails. Different problems which hinder metallurgical efficiency exist in different mills. One such problem occurred in the Bralorne mill at the tailings end of the circuit, where the washing efficiency of the filters was so low that serious losses in dissolved gold occurred.The new cyanide plant at Bralorne went on stream in August 1961. Test work done showed that: a flowsheet of grinding in water, jigging, thickening, agitating, followed by double filtration, gave satisfactory results and was more economical than a counter current plant. Two filters, 141 x 161, with approximately 700 square feet of filtering surface on each, were purchased and installed in series. Test work showed that this was ample filtering area for 500 tons per day.When the plant started up a density of 45% solids was maintained in the agitators, and a 20 ounce cotton dl1ck was used on the filters. Vacuum was between 23 - 25 inches. Under these conditions the filters would not work and only picked up a very slight skim of pulp. Various speeds were experimented with, 4 minutes per revolution being the most efficient. At this speed the thickness of the pulp on the filters increased to about 1/8”• It was therefore quite apparent that, under these conditions, the filters would not handle very much tonnage and the mill tonnage would have to be reduced drastically until the problem was solved."

Jan 1, 1967