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By Seppo Lähteenmäki, Pertti Koivistoinen, Jaakko Levanaho

"This paper describes the benefits and disadvantages of fully autogenous grinding when compared to grinding with steel grinding media. The study is a real case study based on a low tonnage, high grade mining project in a remote location in a developing country. The study compares the capital and operating costs of using either SAG mill, Ball mill, Crusher (SABC) or fully autogenous (AG) grinding circuits and produces an economical analysis of the project for both options. The economics have been developed for the overall project, including mining, processing, environmental and the infrastructure as well as for the additional cost of constructing a fully autogenous grinding circuit instead of the original plan of a SAG Mill, Ball Mill circuit.The paper also describes the development of the autogenous grinding circuit at Outokumpu Oy, Pyhäsalmi mine. This experience was used to design the autogenous grinding circuit for the case study. Pyhäsalmi Concentrator has over 30 years of experience in operating autogenous grinding circuits and therefore provides a sound base for the new circuit design.INTRODUCTIONGrinding of ore using steel grinding media is currently the most commonly used method in the mining industry. Autogenous grinding, ore replaces iron media, is also common especially in Europe and Africa. Iron ore industry in North America uses autogenous grinding in primary and/or secondary stages extensively. In gold, copper and other base metal industries, autogenous grinding is not as common, although there are operations where pebble grinding is or has been used in the secondary grinding stage. There are many variations of autogenous grinding in use in the mining industry. These variations include different mill sizes, mill length to diameter ratios, ore lump sizes, screening and pebble crushing configurations."

Jan 1, 2000

By Chuck Edwards

Whatever your opinion of the validity of the scientific case for global warming, or of the wisdom of the Kyoto Protocol, it would seem judicious to err on the side of caution and try to sensibly minimize global climate change. To this end, we should take prudent steps to minimize our emission of greenhouse gases. Cameco is the world's leading supplier of uranium for use as fuel in nuclear power plants. Cameco’s uranium production fuels nuclear power plants in 16 countries. Nuclear power plants generate clean electricity without greenhouse gas emissions. This presentation describes the role that uranium and nuclear power can have in meeting the growing demand for electricity and at the same time combating global climate change.

Jan 1, 2004

By David Whittle

When does a project with questionable viability, warrant further investment? There are cases in which projects, which evaluate to a negative mean probable value, are worth investing in. There are also cases in which projects that evaluate to a positive mean probable value, should not be invested in. The author will present a model for ?project-control?which includes an adaptation of a well know grade-control concept. Comments on Resources and Reserves ?Resource and Reserve estimates are based on positive information (43-101). ?Reserve and Resource confidence qualitatively assessed. ?U.S. Geological Survey (USGS) recognizes Undiscovered Resources (U.S. Geological Survey 2003).

May 1, 2006

By Lorrie Fava

Two needs in the mining industry, to enable overall process improvements, are open systems and network connectivity in underground mines. The Pando project, a collaboration between Symboticware, Vale and Xstrata Nickel, and supported by CEMI, addresses these issues, and leverages the solution platform to deliver intelligent applications. An open system is one that uses publicly available standards for its key interfaces. Vendor-neutrality and ease of information flow are two main benefits that result from the use of open systems. By facilitating the interoperability of systems, open systems allow information to be available when and where it is needed for decision support. Network connectivity in underground mines is typically limited, with hotspots in strategically chosen areas that are relatively static. Mobile equipment moving through a mining work cycle experiences intermittent connectivity; in this situation, seamless remote equipment monitoring is impossible. The Pando project establishes an open technology platform, adhering to the IREDES and OPC UA standards. It enables the collection and integration of information generated by mobile equipment? seamlessly while there is a network connection, and as a store-and-forward gateway to manage intermittent connectivity. The platform capabilities are leveraged to support embedded intelligent applications. This open platform, the SymBot, is a rugged hardware and software device. The platform complies with open standards for industrial automation and systems interoperability. The SymBot platform is capable of providing advanced real-time decision support at the device level, and is designed to be remotely configurable. Applications being developed through the Pando project include engine monitoring, a dynamic load weighing system, machine location monitoring and automated activity monitoring including production and maintenance reporting.

Oct 1, 2010

By Pierre Gaucher

It is possible to selectively mine an orebody by combining the use of the SSW probe with any bulk mining methods as well as narrow vein exploitations. In other words, thanks to the use of the SSW probe, mining operators will be able to reduce and control dilution that is generally associated to every mining operation. Already, quick and substantial savings have been obtained. Falconbridge mines have demonstrated in Sudbury and Raglan operations, that the SSW probe can log nickel, copper and iron sulphides in blast holes. They have raised the grade and reduced dilution by outlining the limits of the ore zones before selectively loading explosives in the blast holes. By lowering the probe in a blast hole, a profile of the ore content is instantly measured and recorded. Logging cored diamond drill holes at the mine have demonstrated that the ore content (nickel, copper, cobalt, PGM) as assayed is proportional to the intensity of the probe?s electromagnetic response (EM), probably because the nickel / pyrrhotite ratio is uniform within a given orebody. The probe also measures the intrinsic conductivity of the sulphides and the percentage of magnetite. All probe readings are displayed and automatically stored at a 10-cm interval within the same reading unit. A 30-meter blast hole takes less than 2 minutes to survey. The whole instrument is light (12 kg) and very simple to use. One operator can carry the SSW system and survey either down or up-holes. The probe works from ?40°C to +50°C. Plotting the measurements of the SSW probe in blast holes (2-3-4-6-10 inches in diameter) before blasting allows to determine the exact shape of the orebody within the waste rock and uneconomic low-grade ore. Thus, only the portion of the holes that contains ore is blasted. The dilution is then much reduced and, by leaving the waste and low-grade ore in place, the mine saves on transportation, blasting, crushing, backfilling, milling, etc. Thousands of dollars are thus saved. Some savings may also be achieved during the development of stopes by guiding development drifts and by replacing diamond drilling by percussion drilling. In some circumstances, when the probe shows that some of the rich ore was not drilled-off, additional blast holes will allow to recover pockets of rich ore that otherwise would have been abandoned in the walls of a stope.

Oct 1, 2001

By Denis Thibodeau

his paper describes a study of an altered mining extraction and the resulting Rockmass response at VALE?s Creighton Mine. Typically, the deep mining zones have strict stope extraction guidelines to ensure safety and productivity; however, these guidelines offer low flexibility or few options for stope sequencing. The 402 O. B. being in a good rock mass, at moderate depth and stress regime at Creighton, offered an opportunity to drive a more flexible mining sequence with stopes and a pillar. A three-phased approach was used to mitigate risk of the mining plan: 1- Numerical modelling to fully anticipate rock mass response to the proposed mining sequences. 2- In situ seismic monitoring to collect stress and seismic activity data. 3- Analysis of the in situ data to correlate to the modelling results. The creation and the extraction of a pillar in the 402 O. B. was successfully completed. The recorded seismic activity agrees well with the numerical modelling since most of the seismic activity is localised in the hangingwall where the deviatoric stress corresponds to an early damage process. The moderate levels of deviatoric stress cause localised failure with low level of seismic activity.

May 1, 2013

By T. K. Dichmann, J. A. Finch

"Microflotation, laboratory batch, and in-plant minicell continuous tests were conducted to determine if copper ions not only activate sphalerite but also depress pyrite when the minerals are together. Microflotation tests showed that pyrite recovery increased with addition of copper ions in the pH range of 5-10 when alone, but decreased when sphalerite was also present. Batch flotation tests (Red Dog ore) showed that upon addition of copper, pyrite recovery decreased significantly. The continuous tests (Louvicourt Mine) confirmed this and indicated that with excess copper pyrite recovery can increase. The results suggest there is competition for copper and xanthate in favour of sphalerite. To take advantage of this competition it may be necessary to control the sequence and rate of copper, collector, and lime addition. INTRODUCTIONFlotation, in common with all physical separations, is an imperfect process that results in misplacement of minerals. One source of this imperfection is accidental activation by contaminating metal ions. An important practical example is the misplacement of pyrite to zinc concentrates. Flotation of sphalerite generally requires activation by copper ions, added as copper sulphate. Copper ions are also used to activate pyrite [l] hence there is the suspicion that accidental activation contributes to the recovery of pyrite (Py) with the sphalerite (Sp). However, recent literature has shown that copper ions may make Py less floatable if Sp is also present. Xu et al. [2] conducted continuous minicell tests in-plant at Kidd Creek Operations (division of Falconbridge Ltd.) and showed that while the addition of copper sulphate improved zinc/iron selectivity, it did so as much by reducing the recovery of pyrite as increasing zinc recovery (Figure 1)."

Jan 1, 2000

By G. Griffiths

"P. WitteWitteck DevelopmentThe implications of using a tower mill for fine grainding in the ore processing of tailings are significant. What can those of us who are in a research and development situation do when we recommend this equipment to a client? When this prototype is placed on stream next to a conventional grinding mill as you suggest how do we estimate the power requirements and the grind which will be achieved?ReplyLet me explain the Macassa circuit. The tower mill here was running in parallel with one of the ball mills. The feed entering the tertiary system is scalped in a primary cyclone. The finial cut is made in a secondary cyclone. The actual feed to the tower mill is the underflow from the two cyclones and was split to the ball mill and tower mill. During the testing we were unable to isolate the tower mill to determine its contribution to the overall system. We then started to look at the amount of material produced across the mill. We entered the mill at between 17% and 20% finished material and exiting at between 36% and 40% finished material. We were able to project, with a high efficiency classification system, and arrived at 6 Kwh/ton or better."

Jan 1, 1984

By Richard C. Banting

Excessive vibration is known to have an adverse affect on soft body tissue and operators of heavy mining equipment can be exposed to vibration that exceeds levels recommended in international guidelines (ISO 2631-1, for example). Research has found that many of the seat and suspension systems currently used in mine haul trucks and load haul dump vehicles are actually amplifying the vibration. This overview presentation will outline the current research being conducted at Laurentian University and the University of Western Ontario, and the roles of partners in rating the ability of a number of commonly used mine vehicle seats to isolate harmful vibration.

Oct 1, 2010

By M. Veiga, L. Lavkulich, R. Pakalnis, M. Ghomshei, S. Baldwin, J. A. Meech

"On July 26, 2000, the Canada Foundation for Innovation announced an award of $1.3 M dollars for The Centre for Environmental Research in Minerals, Metals and Materials, CERM3, at The University of British Columbia. Additional funding was also provided by the British Columbia Knowledge Development Fund ($1.3 M) and the UBC Stewart Blusson Fund ($0.7 M). Annual industrial grants and contracts are providing support funding for the on-going research projects. Corporate membership in CERM3 entitles each participant to a seat on the technical advisory committee (TAC) as well as access to the five laboratory facilities currently under construction. Both the federal and provincial governments will also participate in the TAC through NRCan-CANMET and the BC Ministry of Energy and Mines, respectively. CERM3’s mission is:• to develop innovative methods to deal with environmental problems created by mining activity;• to promote sustainable development as a hallmark of management decision-making; • to produce mining and processing engineers with the required environmental skills; and• to enhance the image of mining in society as a vibrant and necessary component of a modern economy and society which disturbs the environment for the benefit of mankind.CERM3 brings together a multi-disciplinary team of researchers from over 12 departments at The University of British Columbia (UBC) to work on mining-related environmental problems. These include: chemistry; soil sciences; chemical and biological engineering; earth and ocean sciences; microbiology; civil engineering; electrical engineering; metals and materials engineering; mechanical engineering; mining and mineral processing, the Westwater Research Centre; the Institute for Resources and the Environment; and the School of Occupational and Environmental Hygiene. The centre intends to interact with scientists from industry, governments and other universities across Canada and around the world. CERM3 aims to become Canada’s leading environmental research facility for the mining industry. This paper describes the evolution of CERM3 and its coordinated multi-disciplinary approach to mining and the environment. Some of CERM3’s research projects include:• developing new protocols for environmental analyses to provide consistent and reliable assays;• isolating a natural virus for Thiobacillus ferrooxidans and other bacteria responsible for acid rock drainage (ARD);• designing bio-remediation and adsorption techniques for mine effluents;• promoting and enhancing the use of hydrometallurgy to reduce environmental pollution;• examining new approaches to comminution to decrease energy consumption;• developing a magnetically levitated hoisting system to reduce the footprint of a mine operation;• building a state-of-the-art supercomputer network laboratory for mine/mill simulations; and• designing intelligent bulkheads to seal tunnels following mine closure to survive for 1000 years.This latter project involves the establishment of a research station at the Britannia mine site, 45 km north of Vancouver, which will provide a full-scale facility to design the “Millennium Plug” and contribute directly to the solution to one of North America’s worst ARD-contaminated sites."

Jan 1, 2003

By H. Tan

The effect of carbonaceous matter on gold extraction was investigated in cyanide systems with pure gold as well as pre-robbing sulfide gold ores. Auger studies demonstrated that the carbonaceous matter preferentially smeared on iron sulfide rather than aluminosilicate surfaces during wet or dry grinding. During mechanically mixed leaching, coating of sulfides and silicates and stripping of carbonaceous matter occurred simultaneously. TEM and XPS studies indicated preferential coating in the form of elemental (graphitic) carbon at the edges and the defect sites of particles. Interestingly, carbonaceous matter extracted from the gold ore was predominantly graphite and not preg-robbing in a solution with a high KCN concentration. However, the carbonaceous coating had a significantly detrimental effect on gold dissolution when gold was pre-ground with the gold ore. Artificial coating on gold surfaces with the natural carbonaceous matter from the ore was also found to substantially retard gold dissolution. With the addition of the natural carbonaceous matter from the gold ore, gold extraction from two non preg-robbing sulfide gold ores was inhibited owing to carbonaceous coating. The presence of carbonaceous matter significantly reduced the current density for gold oxidation and increased the current density for pyrite oxidation. This could explain the fact that carbonaceous coating hindered gold dissolution while enhanced sulfide preg-robbing.

Jan 1, 2005

By Vanessa C. Koppe

During ore body modeling normally additional samples are required to improve resources evaluation and mining planning. At this stage one rises the question about where additional samples should be located. Regular sampling pattern seems to be a reasonable choice, since all the regions within the deposit receive the same number of samples without a clear clustering. Nevertheless, values for certain attributes (grades for instance) from a mineral deposits may behave more erratic in some regions than others. Consequently, by adding samples to these regions could bring more benefit for reducing the uncertainty related to a transfer function such as Net Present Value (NPV), instead of adding samples to location of low grade uncertainty. Thus, for a given number of additional data, the test of a regular pattern and a pattern which add samples on areas of high uncertainty of the attribute of interest is worth. This paper presents an algorithm that allows the construction of these two patterns, automatically, on a software commonly used in the mining industry. The algorithm leads to a fast analysis on the efficiency of the two patterns in reducing the uncertainty associated with a transfer function.

Oct 1, 2009

By J. A. Finch, T. Weber

"Bubble size in flotation is strongly influenced by frother concentration in the pulp liquor. There is no accepted method of judging the dosage and thus how effectively frother is being distributed to control bubble size is not known. This will hamper certain plant test work where constant bubble size (e.g., when comparing reagents) is implicit. Bubble size is not easy to measure in plant and gas holdup is suggested as a surrogate in the development of a proposed “meter” to estimate frother concentration. The meter is calibrated to enable frother concentration to be estimated on samples drawn from any location in the flotation circuit. The meter and its calibration are described.As general background the action of frothers in reducing bubble size by retarding coalescence is discussed and the bubble generation systems for which the effect will be important are considered.INTRODUCTIONBubble size is an important variable in flotation. The flotation rate constant k has been related to mean bubble size Db by k % Db -n with n ranging up to 2 (Ahmed and Jameson, 1989) and even 3 (Yoon, 1993). Recent work has introduced k % Sb, the bubble surface area flux, given by Sb = 6 Jg / Db (where Jg is the superficial gas velocity or volumetric gas rate per unit cell cross-sectional area), i.e., n = 1 (Gorain et al., 1998). Regardless of the exact value of n, the significance of bubble size in flotation remains. In many plant trials it will be implicit that bubble size has not changed and attention will focus on other process variables. The measurement of bubble size, or a surrogate, would be useful addition to any test work.The size of the bubbles is influenced by several variables, gas rate, gas injection system (e.g., impeller design and rotation speed in a mechanical cell) and pulp composition (chemicals added, percent solids), but the most important is frother concentration (Harris, 1976). The frother functions by retarding coalescence (see appendix), which acts to preserve the small bubbles generated in the pulp (and permits a stable froth to form on top of the pulp). The measurement of bubble size is thus related to measuring frother concentration. The distribution of frother and whether sufficient (to control bubble size) is reaching the intended parts of the circuit then become important considerations. At present there is no simple way to judge frother concentration in a plant. In this communication we introduce a possible methodology, a “frother concentration meter”."

Jan 1, 2003

By J. Ander

About fifteen years age some mines in western Canada commenced using Diesel engines, partly for development work but also for operations on quite a large scale. In the Eastern mining field, the Diesel engine made its appearance some eight years ago and has since, at quite a number of mining plants, proved to be a reliable and economical prime mover. As a result, it is today used more extensively than could have been foreseen only a few years ago, and it is reasonably safe to predict that the next few years will see the Diesel engine utilized to a still greater extent in the Canadian mining industry. It is not much more than thirty years since the first Diesel engine was put in operation. During the early years of this century, the Diesel engine took, so to say, its first faltering steps in public service. Since then it has reached a high state of perfection, and its importance has grown in a most remarkable way, until today it is used in practically every field where power is required. It is slowly but surely superceding steam for a great many purposes, as, for instance, for ship propulsion. While in 1921 only about 8 per cent of all tonnage launched was motor-driven, the proportion had grown to 38 per cent in 1927, and for 1929 it was slightly over 45 per cent. Some of the finest passenger liners afloat are Diesel-driven. In the early days, Diesel engines were built only in comparatively small units. Today engines with a capacity per unit of up to 10,000 horsepower, or even more, are being built for marine and stationary purposes.

Jan 1, 1930

By Alan D. Akerman

This paper describes the significant advantages and improvements in operational availability, reduced breakdowns, and overall cost reductions that can be achieved through the application of a Reliability Centred Maintenance (RCM) program, including Condition Based Maintenance (CBM) and Equipment Health Monitoring (EHM), in a mine environment. It uses a case study to illustrate the essential elements that constitute the basic requirements to establish such programs. This CBM case study analyzed the Load-Haul- Dump (LHD) vehicle sub-systems and their dominant failure modes, as a precursor to the development of condition indicators. The case study describes a disciplined process to enable condition indicator development and qualification in support of a CBM program. The identified condition indicators vary from readily applicable off-the-shelf monitoring systems and techniques, through to "leading edge" technologies that require further research and development. The paper also explores the developments that have been made in the combination of expert system software associated with modern computer based control systems, and the availability of "intelligent? sensor technology that complement the control system capability.

May 1, 2002

By J-L. Tang

A new rhcoforming processing of Al alloys with component shaping systems apart from slurry preparation systems is experimentally exploited, using the reversible multilevel-speed electromagnetic stirrer, the slurry transfer tool and its coating, the thin plate sample with five steps and rheocasting mould, all of which are independently developed. The results show that semi-solid A356 alloy slurry with shape factor of about 0.85 and particle size of 70~80 µm (under air-cooling condition) could be prepared in 20~25 s, fully meeting the production rate of high pressure die casting. The slurry could be smoothly transferred from the slurry preparation equipment to the rheocasting shot chamber while the slurry temperature of slurry decreases by no more than 3 . The tensile strength and elongation of the semi-solid rheocasting samples could be respectively increased by 11.6~18.2 % and 42.5~50 % compared with the traditional liquid die casting ones, and the rheoforming processing has close affinity with the traditional hot working processes.

Jan 1, 2007

By C. Larsen, R. A. Walker, A. Voth, C. Daoust

"The 3000 t/d mill at Hernia Gold Mines Inc. was commissioned in March, 1985. By Canadian standards the concentrator is highly automated, however, unlike the retrofit systems in many other plants, the Hernia process control system was installed during plant construction. This paper describes the Hernia control system beginning with system development (justification, architecture, start up, etc.), proceeding to current applications (crushing, grinding, leaching, etc.) and finally discusses some of the short term objectives for system improvement.INTRODUCTIONThe Hernia Gold Mines Inc. operation is located in the Marathon area of Northwestern Ontario. Controlled by Noranda Minerals Inc. (50.1 %), the cost of bringing the mine into production was nearly $300 million. A unique feature of the mine development was the extraordinarily short elapsed time of three years from Noranda's initial involvement to the start of milling operations. Additional background information on this project can be found in the trade literature (e.g. Tinter (1986). Scales (1987).)The Hernia concentrator is designed to process 3000 tpd of ore and commenced operation in March, 1985. Figure 1 provides a general plant flowsheet indicating the major circuits. Typical annual production statistics are included on the figure and these have been extrapolated from the available 1987 year-to-date data. Larsen and Tessier (1986) have previously described the operational aspects of the mill.In a metaphorical sense, the Hernia concentrator is like the traditional bride, ""wearing something old (e.g. the cyanide leach process), something new (e.g. a plant wide digital control system installed during construction), something borrowed (e.g. crushers from Gaspe) and something blue (e.g. the cladding on the surface buildings). While the prospect of fully undressing this bride is of considerable interest, here we choose to focus on something new. In particular, we choose to examine the process control system in some detail since Hernia is one of Canada's more highly autcmated gold mills. The control system is of interest because it has received suostantial credit for maximizing metal production and minimizing operating costs. With reference to the latter, it is worthy of note that Hem lo reports recent operating costs of less than $100 U.S./oz."

Jan 1, 1988

By David A. Edgecombre

This paper discusses modern practices in the extrusion of steel. Particular emphasis is given to a description of the Ugine Sejournet method of extrusion, involving the use of glass as a hot work lubricant. Other methods are also mentioned. A brief history of extrusion is presented; present practices in the quality extrusion of tubing and solids are described; and the future potentials of the) process as a tonnage producer are briefly discussed. The advantages of extrusion and the reasons for the use of a glass lubricant, as well as the various methods of using glass, are given. The process, as described, is being used in the manufacture of large commercial quantities of stainless steel tubing and sections. This extrusion process is an essential and unique means of forming such atomic-age materials as titanium, zirconium, molybdenum and other super alloys all of which are materials required in the creation of nuclear installations.

Jan 1, 1963

By R. N. Murarka

"Hydrocyclone modelling and selection procedure is illustrated. Computerized procedure for hydrocyclone cut size determination for grinding and non-grinding applications is described.A standard procedure for evaluating operating hydrocyclones is described in detail. Many case studies are illustrated comparing actual plant performance with the computer simulation output in terms of overflow product size distributions.INTRODUCTION Cyclones are widely used for applications such as: close circuit grinding, backfill, tailings and dewatering. Normally, cyclones are used for very fine separations where screens are not suitable or too expensive. Figure 1 shows the separation size range of various classifying devices. Cyclones are popular because of their low capital and operating cost. Cyclone selection procedure for different applications depends on the amount of information available on the cyclone feed slurry characteristics. Closed circuit grinding applications will be discussed in detail in this paper. The Cut Size:The size of the material in the feed which reports 50% to each product stream (i.e. underflow and overflow), after correcting for the feed solids by-passing with the underflow liquid, is termed the cut size or ""d50c"". This is often used as the criterion and the basis for cyclone design.When the corrected recovery to underflow of each mesh size in the feed is plotted against the geometric mean size in microns on a log scale, the micron size corresponding to 50% recovery is the d50c size."

Jan 1, 1992

By Farzaneh Abedini, Narain Hariharan, Lucas C. McFarlane, Nikolas A. Romaniuk, Tiffany Thayne

The use of dewatered mine tailings as backfill material (commonly referred to as ‘paste’ backfill), is the most practiced form of backfill in Canada providing significant environmental benefits by reducing the size of external tailings facilities and improved economics through enhanced resource recovery. Paste backfill operations reuse filtered mine tailings with a cementitious binder and water to create a slurry that is hydraulically transported to refill underground stopes, later forming a structural network of cemented tailings in the mine stopes. Unlike typical structural applications that utilize General Use (GU) Portland cement; modern paste backfill operations maximize strength performance by blending Portland cement with ground granulated blast furnace slag (GGBFS) or other supplementary cementitious materials (SCMs). GGBFS and other SCMs offer key performance benefits and carbon reductions; however, the availability of these SCMs is rapidly dwindling in today’s carbon-constrained economy. This paper examines the development of an alternative binder system that provides similar performance and carbon reduction to that of GGBFS for mine backfill operations. The binder utilizes the chemical reaction between a reactive source of aluminosilicates and available calcium from calcium oxide or calcium hydroxide to replace between 50 to 100% of GGBFS. The performance of the binder is examined with insights into the hydration mechanisms that generate mechanical strength in the cemented paste network. Paste backfill slurries require precise engineering to create a material that maintains flowability during pipeline transport and generates enough strength to meet operational targets once placed in the stopes. Engineering of such slurries requires large amounts of water to be added to the binder-tailings matrix, far exceeding the typical water to binder ratios used in concrete mix designs. This characteristic of paste backfill warrants great emphasis on understanding the hydration mechanisms of the binder used in the paste backfill system. GU cement is typically composed of 50-70% tricalcium silicate and 15-30% dicalcium silicate.  The hydration mechanisms of these compounds consume 4 to 6 units of water to mineralize into calcium silicate hydrate cemented phases that result in compressive strength development. Cementitious aluminate and aluminosilicate phases make up 5-20% of GU cement and aid in secondary performance characteristics such as set time. Certain calcium aluminate hydrate phases such as monocarboaluminate and ettringite mineralize 10 to 32 units of water into their crystalline structure. Hydration products such as ettringite are traditionally avoided in construction applications due to their propensity for volumetric expansion after cement setting, leading to micro-fissures and subsequent strength degradation (known as ‘sulfate attack’). This paper proposes that such hydration products benefit the strength development in paste backfill slurries with the aforementioned characteristics due to their greater potential to mineralize free water. The newly developed calcium aluminosilicate binder is designed to replace 50-100% GGBFS or other SCMs used in paste backfill systems and meet operational strength requirements by providing exceptional hydration characteristics through cementitious reactions. Additionally, the aluminosilicates used have a minimal carbon footprint and a secure supply outlook, thereby allowing mine operators access to a low-carbon binder option throughout the mine’s lifespan.

May 4, 2025