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By A A. Latscha, D O’Connor

Increasing orebody complexity, restrictions in ground access, and longer lead times for disturbance approvals, have generated the need for the Resource Development Team within Rio Tinto Iron Ore (RTIO), to explore optimised drill design techniques that deliver resource conversion value while maximising program outcomes. In response to this challenge, the Team initiated a case study to produce an AI assisted/designed drill program using a non-machine learning AI. The case study involved the assessment and implementation of an AI generated drill program at one of RTIO’s Pilbara iron ore deposits, located in the Hamersley Province of Western Australia. The Mineral Resource is currently classified as 100 per cent Inferred. Access constraints inherent to topography, and the presence of exclusions zones have prevented adequate drilling coverage, resulting in lower resource confidence and a poor definition of the orebody extents and geometry. The drill campaign, planned in Q1 2023, needs to consider access constraints, complex topology and the limitations related to additional ground clearance, while addressing the requirement of improving orebody knowledge. The drill plan had to address two objectives. The first and main aim of drilling was to upgrade the Resource Classification to allow for possible conversion to Ore Reserve. The input for this objective was a volumetric representation of the areas currently not meeting pre-defined quantitative Resource Classification upgrade criteria. The second objective was to better define the orebody extents and geometry. For the second objective, the input to the drilling optimiser was a volumetric representation (blocks) of the areas of high uncertainty in the mineralisation/waste boundary, which were defined using an indicator conditional simulation technique. The drilling optimiser output was a range of compliant drill plans. A set of KPIs based on economic and orebody knowledge criteria were used to assess the plans and to select the most optimal drill design to be drilled in 2023. The geology and management teams were able to make better informed, objective decisions using the trade-off between cost and orebody knowledge gained. As part of the assessment, the AI generated plans were compared to our current planning practises. The AI assisted plans, when gauged against the project KPIs, showed clear and measurable improvements in both meeting project objectives and in managing operational risk.

May 24, 2023

By E. L. Bruce

Introduction The Outokumpu copper mine is situated in eastern Finland, 50 kilometers west of the city of Joensuu or 225 kilometers directly north of the city of Viborg (Viipuri), which is situated at the eastern end of the gulf of Finland (Figure 1). The ore-body was discovered in 1910 by Dr. Otto Trüstedt after two years of careful, scientifically-directed, search. During the early period of development of the mine, the ore was treated locally and the copper re-covered by an electrolytic process. Now the ore is concentrated by tables and by flotation. The concentrates are shipped to Germany for refining. In 1929 the mine produced 150,000 tons of ore from which between 20,000 and 25,000 tons of flotation concentrates containing 20 per cent copper were produced. Profits in 1929 were approximately half a million dollars, but the present price of copper will affect very seriously the profits for 1930. The ore reserves are given as between 7 and 8 million tons (1). The grade of ore is stated to be 4 percent to 6 percent copper, with a little zinc.

Jan 1, 1931

By H. T. McAdams

The logic of regression analysis as an operations research tool is critically examined, and a formal basis for its application to mining problems is developed. The traditional view of regression analysis as a statistical discipline does not provide an adequate basis for evaluating a regression model in a specific area such as ore reserve calculation or process control. In particular, the validity of the residual-sum-of-squares criterion is questioned, and the need for a criterion based on interpolative features of the model is emphasized. Strictly speaking, a regression model is statistically supported only at points at which observations are available, yet inferences are drawn with regard to a continuum. When considered as a mathematical function, therefore, the model is observationally defined only on a domain consisting of a finite number of points. Extension of this domain to an interval of the real line must be based on physical rather than statistical argument. Vector space and function theory concepts useful as a logical framework for a physically oriented problem analysis are discussed and their usefulness demonstrated in a practical problem.

Jan 1, 1966

By Albert H. Fay

Through the hearty cooperation of the State coal-mine inspectors, the bureau is able to present in this paper a a complete statement of the coal-mine fatalities occurring throughout the United States during the calendar year 1919. The reports received from the inspectors for the year just closed show a reduction of 10.58 per cent in coal-mine fatalities as compared. with 1918, while in 1918 the reduction was 4.3 per cent from 1917 figures. The total number killed was 2,307 in 1919 and 2,580 in 1918, a reduction of 273. There was a decrease of 128, or 25 per cent, in fa tali ties resulting from mine cars and locomotives, and a decrease of 198, or 15 per cent, in the fa tali ties due to fall of coal or rock. Surface accidents show a decline of about 25 per cent as compared with the previous year. There were, however, increases in accidents due to gas and dust explosions and also explosives. There occurred during the year nine disasters in which five or more men were killed, representing a total of 201 fatalities. The worst disaster of the year was the one occurring at the Baltimore Tunnel No. 2, Wilkes-Barre, Pa., resulting from the explosion or burning of a number of kegs of powder, by which 92 lives were lost. This disaster emphasizes the need for stricter regulations relating to hauling men and explosives into the mine at the same time. The question of whether electricity was responsible or not does not affect the consideration of the various dangers which arise in underground transportation and handling of explosiveB. At best the handling and hauling of explo.sives is hazardous and such being the case, no one, other than the necessary attendants, should be permitted to ride in cars or cages transporting explosives. As a result of this disaster, the report b of the coroner's jury to the governor of Pennsylvania brings out some important dangers to be avoided in the use and transportation of explosives.

Jan 1, 1920

Access to accurate real-time information is critical to maintaining efficiency and competitiveness in any modern minerals processing facility. At MMG LXML Sepon Copper Operation in Lao P.D.R., controlling the copper grade of the feed to the leaching circuit is paramount for maximising productivity and copper recovery. Since 2008, real-time analysis data has been available to process engineers from the Geoscan on-belt analyser installed on the Copper Mill feed conveyor. Access to accurate real-time results from the Geoscan has allowed the process engineers to strictly control blending based on copper grade to overcome variability in the plant feed, where conventional sampling and laboratory analysis is difficult, error prone and time consuming. In addition to enjoying these benefits since the Geoscan’s installation, in recent times the process engineers have expanded the use of the Geoscan by observing elemental results other than copper grade to control different aspects of the operation, focussing on the reduction of Gangue Acid Consumption. This paper discusses the process of expanding the Geoscan use at the operation, including an explanation of the calibration process. Additionally, a brief description of the Geoscan and its use at MMG LXML Sepon Copper Operation is provided, as well as a summary of recent calibration and analysis results. A discussion of future works concludes the paper.

Jan 1, 2016

By L. D. Tracy

"IntroductionOne of the problems which the coal-mining industry must solve in the next few years is the redaction of its ever-increasing timber bill. This includes pit posts, mine tees, timber sets, and brattice boards. As an example of this increase, the following table of timber prices from the records of a coal company in western Pennsylvania, in a district where the supply of most of the different kinds of timber used can be shipped from points within the State, is self-explanatory: Present conditions seem to indicate the continued upward trend ox the cost of mine timber, although the regrettable calamity that has visited the chestnut timber in Pennsylvania may temporarily hold the price of some types of mine timber on a level basis. On account of the chestnut blight, many farmers will undoubtedly begin to convert their chestnut trees into timber before they become a total loss. This may provide, for the time being, a sufficient supply of mine timber to check the steadily rising prices.The local lumber producers are turning their attention to the production of the larger sizes of timber and lumber on account of an unfavorable price on mine ties. From the foregoing table, it is seen that the average advance in the price of ties during the period 1914 to 1920 is 52 per cent, while timber sets and mine car plank increased in value 60 per cent. Amore striking illustration is the fact that a 6 by 8 inch by 6 foot tie sells for 42 cents or at the rate of $17.50 per 1000 board feet; yet mine car plank and timber sets have a value of $48 per 1000 feet, an advantage of $30.50 in favor of the heavier timber.The supply of coal in Western and Central Pennsylvania will last for a long period and it is for the possible future demand for timber that the coal companies must provide. While steel, concrete, and other materials may, in many cases, prove an acceptable substitute, there is no doubt that timber will always be in demand."

Nov 1, 1926

By John L. Walter

A sintered compact of iron containing 0.007 vol fraction of glass , prepared 6). powder rnetullurgtcal lechniques, was rolled lo foil, 0.001 in. /hick. The foil sullrples were anneuled a1 650° to 850°C in hydrogen. Pri,narj recryslullization prodtnced large grains which Lc3ere highly elongnled in the rolling direclion und which had an unusual prgferred orientation. The glass parlicles assumed a stringerlike dispersiorz on working; llie slrinyers were parallel lo the rolling direction and to the long axis of the grains. The same unusual grain structure, preferred orientation, and stringerlike dispersion of purticles are found in heal-ily rolled and annealed foil of tungsten which has heen doped wilh small amounts of aluminum, silicon, and polassiutvt. Both the proper dispersion of the particles and severe working (reductions in excess of 98 pct) are necessary to produce the elongzcted grain structure. RECENTLY, the author reported on the origin of the elongated or "nonsag" grain structure in tungsten foil which was doped with aluminum, silicon, and potassium.' It was observed that particles, identified as mullite (Al6Si2Ol3), were present in the doped ingot (as sintered) and at all stages of processing from ingot to sheet or wire. It was shown that the particles, being plastic at tungsten working temperatures (up to 1550"C), underwent a "stringing out" parallel to the working di-direction. It was concluded that these strings of particles were responsible for the formation of the highly elongated interlocking grains observed in doped tungsten wire or sheet. To give further credence to this explanation of a long-observed but not understood phenomenon, it was decided to design a new system, one which was analogous to the doped-tungsten system. Thus, a bcc metal, iron, was chosen to be doped with glass which would be plastic at reasonable working temperatures for iron. The glass chosen was a #0080 Corning lime glass which melts at about 810°C. This is approximately the same fraction of the melting point of iron (0.6) as the melting temperature of mullite is of tungsten. It will be shown that all the observed unusual features of the doped tungsten are duplicated in the glass. doped iron, even to the preferred orientation of the grains in the recrystallized sheet. In the tungsten sheet the preferred orientation consists of two components, (1i3)(691) and (013)(362), neither of which has been observed as a component in textures of primary recrystallized bcc metals. EXPERIMENTAL PROCEDURE The glass, in the form of fine powder, was added to high-purity electrolytic iron powder and mixed dry. The particular composition chosen was 0.007 vol fraction of glass. After mixing, the powder was mechanically pressed to a disk 0.5 in. diam and 0.15 in. thick at a pressure of 5000 psi. The pellet was sintered, in pure dry hydrogen, for 2 hr at 8 50°C. The sintered pellet was then heated to 750°C and rolled to 50 pct reduction of thickness in two passes, with reheating between passes. The rolling temperature was then reduced to 600°C and the slab was rolled to a thickness of 0.050 in. Rolling to 0.010 in. was accomplished in several passes at 300°C. Final reductions to 0.003 and 0.001 in. were taken at room temperature. This rolling temperature schedule was similar, in terms of the fraction of the melting point, to that used in the rolling of the doped tungsten. The total reduction of thickness was in excess of 99 pct. Samples of the rolled foil were lightly electro-polished and annealed for 1 to 6 hr at temperatures of 650" to 85O°C in hydrogen. Samples for transmission electron microscopy were thinned on a Disa Electropol using AC-1 electrolyte.

Jan 1, 1968

By W. C. Phalan

"Prewar Conditions:Metallic magnesium may be considered a war metal, but a war metal with a future, so far as the industry in the United States is concerned. Its production in the United States prior to 1915, on a commercial scale, was negligible, but imports prior to that year may be taken as a gaze of the demand for the metal. Unfortunately, magnesium was not listed separately by the Department of Commerce prior to the war, among the importations, but was included with other metals, as follows: ""Barium, calcium, magnesium, sodium, and potassium, and alloys of which said metals are the component materials of chief value."" However, the imports of metals enumerated other than magnesium were probably small, so that the importations under the above caption may be considered chiefly metallic magnesium in one form or another and, therefore, is an approximate gage of the demand for the metal in the United States. These imports were as follows:These figures are so close that they give a good idea of the figures for the respective calendar years.Of this prewar use, it has been estimated that about 85 per cent was used annually and in approximately equal quantities in the production of (1) flash-light powder, (2) fire works, (3) aluminum casting work, and (4) nickel and nickel-copper alleys, such as monel metal, etc. The re¬maining 15 per cent was employed for general uses, such as deoxiding brass and other copper alloys in foundry work, and to a small extent in laboratory and research work."

May 1, 1920

By Dewa Putu Agus Sudarmaja, Widi Astuti, Januarti Jaya Eka Putri, Yayat Iman Supriyatna, Himawan Tri Bayu Murti Petrus, I Wayan Warmada, Siti Nurul Aisyiyah Jenie, Ferian Anggara, Anisa Maulidia, Vincent Sutresno Hadi Sujoto, Sutijan

With the rapid development of renewable energy technology, such as electricity reserves, to store energy for electric or electric vehicles, environmentally friendly energy sources are expected to continue to be fulfilled according to mobility and stationary energy needs. Lithium is the most attractive candidate for energy storage development. The presence of lithium in Indonesia in the Sidoarjo mud content is interesting to be used as an alternative source of raw materials. During the research, sulfuric acid acted as a solvent, and hydrogen peroxide acted as an oxidation agent. Lithium recovery will be studied using a leaching process at various temperatures (30, 45, and 60 °C) and sulfuric acid concentrations (0.5, 1, 2, 3, 4, and 6 mol/L). The increasing temperature, sulfuric acid concentration, and hydrogen peroxide concentration will directly affect the lithium recovery. An increase in sulfuric acid concentration will be directly proportional to the recovery of lithium in the solution. Optimum conditions were obtained at varying 6 mol/L sulfuric acid concentrations and 60 °C temperature variations. The shrinking core model (SCM) studied leaching kinetics, and ash layer diffusion acted as a rate-controlling process. The activation energy of the leaching process was obtained at 38.90 kJ/mol.

Jul 25, 2023

By Stefan Schwank, Alexander Blatt, Franz-Werner Gerressen

Diaphragm wall technique is usually used to install diaphragm walls, which are known as underground structural elements commonly used for retention systems and permanent foundation elements as well as deep groundwater barriers, named Cut-Off-Walls (COW). In this exploration project, the diaphragm wall equipment was used in the 2019 summer season to perform the first part of an exploration and bulk sampling program for a potential mine on the Star Kimberlite. Beside the idea of using the diaphragm wall technique as bulk sampling equipment, the sampling program required the adaption of equipment and tools for a depth capability never reached before by a trench cutter in any commercial application worldwide. The paper will explain the development of the sampling program as well as the challenges occurred with the local geology and the specific demands of the exploration and sampling program. It will also provide an overview of the lessons learned during the 2019 season and will give an outlook to the approaches of optimization for the second phase which will be carried out in 2020.

By Frederick J. McGarry, Fred Moavenzadeh

An experimental investigation of the thermal and mechanical responses of rock materials to laser radiation is described. Specifically, the following three topics have been studied in detail: 1. Temperature measurements on thin discs subjected to laser radiation. 2. Strain measurements on thin discs subjected to laser radiation. 3. Observation and evaluation of cracking and spalling phenomena in constrained and unconstrained thin discs respectively, subjected to laser radiation. In conjunction with the experimental work done, use was made of a heat flow analysis and a stress analysis program developed for this purpose. It was possible to theoretically predict the thermal and mechanical responses of a rock specimen to laser radiation and then compare them with experimental observations. Good correlations were obtained.

Jan 1, 1971

By M. Pakala, Z. Fan, Ray Y. Lin

Deposition of hard chromium coatings using electrodeposition is accompanied by emission of hexavalent chromium mists which is a carcinogenic. Hence alternative chromium deposition technologies are being investigated. Sputter deposition is a strong candidate to economically deposit hard chromium coatings in an environmentally friendly way. Chromium coatings of 2-3 µ m thickness were deposited on plain carbon steel coupons using RF magnetron sputter deposition. Depositions were carried out with 0 to 22 vol% nitrogen in the plasma. Structure of the coatings was studied using x-ray diffraction analysis With increasing nitrogen contents, formation of the two nitride phases was observed. The pure chromium phase was detected in coatings with up to 7% nitrogen in the sputtering gas. The solid solution of nitrogen in the pure Cr phase coating was identified by shifts of Cr x-ray diffraction peaks to higher d-spacing. The microhardness of the coatings deposited at a substrate temperature of 200°C showed an increase in hardness with increasing nitrogen content from 600 kgf/mm2 (5.9 GPa) at 0% nitrogen to I250 kgf/mm2 (I2.25 GPa) at 9.5 % nitrogen and a subsequent decrease in hardness to I 100 kgf/mm2 (11 GPa) beyond 9.5 % nitrogen in the sputtering gas. This corresponds to the formation of the hard Cr2N phase, at 9.5 % nitrogen, and CrN phase, at I5.7 % nitrogen. The reported bulk hardness values of Cr2N and CrN are I600 kgf/mm2 (I5.7 GPa) and I 100 kgf/mm2 (11 GPa) respectively. For pure Cr phase coatings, there is a slight increase in hardness for coatings deposited at 7. I % nitrogen from that without nitrogen in the sputtering gas. This could possibly result from the solid solution strengthening of the Cr lattice by nitrogen. For films deposited at 200°C, phases of the deposited films seem to be the overwhelming factor in controlling the microhardness.

Jan 1, 1998

By B. Bag

Saturated and unsaturated fatty acids are used in the flotation of iron values present in iron ore. Among the several fatty acids, oleic acid and its sodium salt are widely used. To substantiate the flotation results, the quantum chemical calculations of a few such acids have been carried out by adopting the semi-empirical AM1 method. These acids have been further optimized in the presence of an iron atom. The electronic interaction of the polar carboxylic head group of oleic acid with the iron atom is higher compared to the other acids. The numerical results support the flotation behavior of iron ore with oleic acid. Key words: Iron ore, Flotation, Fatty acids, Quantum chemical calculations, Semi-empirical AM1 method

Jan 1, 2009

By K Higuchi, K Saito, O Ishiyama

Iron ore in Australia is predicted to increase in its phosphorus content in the near future, which is detrimental to properties of steel product. Steelmakers are concerned by the content of phosphorus in iron ore will exceed limits for steelmaking and increase the converter slag ratio to molten steel, which will finally lead to a decline in competitiveness in high-grade steel production. In this paper, fundamental development of a dephosphorisation technique by reduction gasification is considered. Basic reduction examination was carried out using Australian and a synthetic model iron ore sample with phosphorus compound reagent, varying reaction time and composition of substances to find out suitable process condition for dephosphorisation. With successful lowering of phosphorus concentrations by gasification reduction of the iron ores, dephosphorisation was assumed and further elucidation works were carried out. More than 10 mass per cent of dephosphorisation ratio is obtained from Australian iron ore through batch-type 25 g furnace experiment using hydrogen as a part of reducible mixed gas. Lowering of phosphorus content occurred preferentially either in wustite or in another reducing zones, suggesting a relationship between reducing conditions to efficient dephosphorisation of iron ores. Another result of the fundamental experiment using a model sample with reagent is different dephosphorisation occurred with different reagents contributing to with unified reduction model for phosphorus, providing positive possibility for comparative evaluation, even if new morphologies of phosphorus in iron ore are clarified in future. According to these approaches, it is important to reduce iron ore efficiently and to avoid gasified phosphorus retaining and reattaching to adjacent iron ore particle at the same time. A kiln-type furnace is suggested to overcome previous technical issue, and additional experiments using larger rotating furnace were carried out for verification.

Sep 18, 2023

By H. L. Ludtke

Microlaminate composites were fabricated by electron-beam physical vapor deposition. The microlaminates consisted of five layers, each 2 to 4 pm thick, and were composed of either pure metal layers (Cu-Ag), or alternated between metal and intermetallic layers (Nb(Al)- Nb3Al). The microlaminates were heat treated in an Ar atmosphere for 2 to 12 hours, at temperatures of 600°C for the Cu-Ag and 1000°C to 1200°C for the Nb(Al)-NbsAl. Microlaminates were examined after deposition and after heat treatment by scanning electron microscopy and energy dispersive x-ray spectrometry. The effects of heat treatment on the morphological stability of these composites will be described.

Jan 1, 1999

By John M. Hartman

(Read at the Wilkes-Barre Meeting, May, 1877.) Two systems are used for heating air in blast-furnace operations I. The double surface system, in which a cast-iron pipe is heated on the outer surface, and, at the same time, heats the blast from its inner surface. This is simple in operation and gives a continuous effect, but is limited by 1100° F. as a maximum temperature of the blast. II. The single surface system, by which large surfaces of fire-brick are heated, and air passed over the heated surface, absorbing the heat and carrying it on to the furnace. This system is more complex than the double surface, as it involves the reversing of the air and gas every hour and a half. The single surface system has two advantages: 1. The blast can be heated to a temperature of 1800° F. 2. The stoves are indestructible. From recent experience it has been found that 1300° F. to 1400° F. is the best average temperature for economy of coal for safe work¬ing. This is equivalent to a saving of 12 to 2 cwt. of coal per ton, of iron over the extreme limit of cast-iron stoves. Independently of this, it is a strong point in favor of this system that the blast can be raised to a temperature of 1800° F. within an hour when the hearth is getting cold. All furnacemen know the value of a hot hearth for quality and quantity of iron. Cooling of a hearth occurs from leaky tuyeres, scaffolds, or heavy burden. When there is not sufficient coal at the tuyeres to seize on the oxy¬gen of the entering air and convert it at once to carbonic oxide, there will not be enough heat to liquefy the cinder. Black cinder and poor iron are the results. The remedy is additional heat from the blast. If the stoves will give 1800° in place of 1100°, it is obvious that the furnaces will get around sooner, and without waiting for a change of burden at the tunnel head to bring extra coal to the hearth. The heat absorption caused by a leaky tuyere will chill the hearth and drive the zone of fusion higher up in the furnace. This loss must be supplied, and the calories lost to the hearth must be regained before good iron can be made. Take another case : A furnace carefully burdened on No. 1 iron, during a spell of damp weather, goes on to No. 2 or No. 3. Heat is lost to the furnace through absorption by the moisture, and less burden must be carried in order to get back on No. 1. When the

Jan 1, 1878

The mining and minerals extraction industries have often been demonized by the public as industries that put profits and production before people. It is true that the inherent danger of the work has led to more fatal accidents than anyone associated with the industry would care to remember. But, in stark contrast to what has often been said, the truth of the matter is safety is now the top priority of every miner, from the face of the longwall to the executive boardroom. Without safety, nothing else matters. This message was told and retold by representatives from some of the world?s top mining and petroleum companies from Oct. 11-13 during the inaugural Safety and Reliability in the Mining and Resources Industries Conference in Calgary, Canada. The meeting was hosted jointly by the Canadian Institute of Mining, Metallurgy and Petroleum (CIM) and the Society for Mining, Metallurgy, and Exploration (SME). It was the first of a series of conferences to focus on these important topics. Next year, the conference will be held in Minneapolis, MN from Nov. 13-15.

Jan 1, 2011

By B. Slaker, M. M. Sears, G. Rashed

Ground falls represent a significant hazard at underground mines in the stone, sand and gravel (SSG) sector in the United States. Researchers from the U.S. National Institute for Occupational Safety and Health (NIOSH) are conducting detailed investigations into the complex loading conditions at underground stone mines operating in challenging conditions. This paper presents the application of numerical modeling to analyze pillar and roof stability at a dipping underground limestone mine.

By D. L. Stevens

Following an in-depth scenario and strategic-planning exercise in 1997, Noranda's mine production goal was set at 500 kt/a (550,000 stpy) of both copper and zinc metal in five years. There had been no recent discoveries, reserves were shrinking and things had to be done differently and quickly. Change is now continual in Noranda's program. The following steps were taken: the exploration and business development groups were combined, teams were formed to search for and respond to opportunity; geologists were coached to become more business minded and engineers were coached to become more optimistic; the company went global; clear thresholds were set, marginal properties were farmed out and other properties were fast tracked; reconnaissance exploration was focussed where there was a clear competitive advantage; and Noranda became a "flexible" partner to juniors and seniors. Is it working? A number of successes, near successes and outright failures are discussed. The main result is a much higher rate of opportunity flux, which is essential for success in the mining industry.

Jan 1, 2000

By P Goblet, S A. Séguret, E Cordier, A Galli

In salar-type deposits, lithium grades can be measured by bailers introduced at different elevations in the drill holes at locations where, later, the brine will be pumped out to recover the metal. When they are duplicated, these a priori rudimentary measurements may show large differences without indicating whether this is due to the procedure itself or to some physical causes linked to the dynamic behaviour of the salar (seasonality, rainfall, underground flow etc). In the reservoir presented in the paper, the problem is complicated by the double lack of stationarity of the lithium grades: the grades not only increase importantly with the depth but at the same time their fluctuations decrease, making it necessary to use non-stationary geostatistical techniques to simulate them. Reservoir simulation is developed in two steps: first, geostatistical simulations of the lithium grade create possible realisations of the reservoir; then, each geostatistical simulation is followed by a pumping simulation that calculates, at each drill hole of a given extraction scenario, the lithium produced each year over 40 years. For the set of 100 simulations produced in this way, a scenario reduction is made to choose the five most representative simulations where more complex calculations will be carried out (for example, changing hydrogeological parameters such as porosity and permeability, or the elevation of the filters, the number and the location of the pumping and the reinjection drill holes etc). The paper first presents an analysis of the geostatistical model sensitivity to the grade uncertainty when measured by bailer. Among the 100 measurements at our disposal covering the future production domain, 50 per cent are duplicates measured at the same place but at different times. They are randomly sampled to produce five subsets of 75 values, which will constitute the future 3D conditioning points for the geostatistical analysis and the simulations. For each subset, trend, standard deviation and variogram models are fitted, leading to five sets of 20 geostatistical simulations of grades. In this way, the reliability of the different parameters involved in the procedure is evaluated, as well as its impact on the pumping results. Then, a reconciliation study is conducted between the non-stationary nugget effects encountered in the 3D variograms of the lithium grade and a pure statistical analysis of 25 duplicates measured at different locations and/or different times. The result is that if the nugget effect reaches 20 per cent, which is the case of three conditioning subsets out of five, the reconciliation is good and the nugget effect of the variogram model represents the bailer uncertainty, ie the measurement error. Since the geostatistical simulation incorporates a nugget effect, it handles the bailer uncertainty and the impact on the produced metal is included in the evaluation. The final conclusion is that, after the hydrogeological pumping simulations, the initial differences between the five geostatistical models do not influence the final results: lithium grades measured by bailers can lead to a robust evaluation of the extractable resources, a conclusion that conflicts with conventional wisdom.CITATION:Séguret, S A, Goblet, P, Cordier, E and Galli, A, 2017. Bailer uncertainty evaluation in a lithium salar deposit, in Proceedings Eighth World Conference on Sampling and Blending , pp 395–402 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2017