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By P. Minkkinen, R. C. A. Minnitt

Particle size distribution analysis is important to many industries for assessing product quality, process efficiency, and compliance with contractual standards, while ensuring sample accuracy, and representativeness. Inaccurate particle size distribution results, arising from fines due to excessive handling can lead to penalties and buyer-seller disputes. A non-representative particle size distribution means samples will not accurately represent the chemical components either. Sampling blasthole cuttings poses challenges due to large material volumes, segregation, and uneven settling of particles in dense gold bearing ores. Commonly used sampling methods, such as spear or sectoral sampling, may lack representativeness. Particle size distribution analysis is crucial for evaluating sampling methods by comparing test sample representativeness against a reference standard derived from multiple particle size distribution analyses. Acceptable samples must fall within the 97.5% confidence intervals of the standard; deviations analyses lying outside these boundaries indicate a strong likelihood of segregation errors. A case study demonstrates this approach by using a 6.005 kg benchmark sample to assess two additional samples (1 kg and 5 kg), highlighting particle size distribution’s role in detecting sampling errors and refining protocols. An example of three test samples collected from reverse circulation drill cuttings compared to a standard reference sample is presented to illustrate a quality assurance/quality control procedure for reverse circulation drilling.

Oct 2, 2025

By Derrick Chambers, George Kevin Chapin, M. Shawn Boltz

Seismic monitoring is one of the few noninvasive technologies with the potential to provide sub-surface geomechanical information to operators of large open-pit mines. Although passive seismic data has been used to refine emerging failure geometries and provide advance indication of surface deformations in the literature, doing so reliably in an operational context is much more difficult. This is due in part to difficulties in estimating and interpreting source locations and parameters in complex, low-stress open-pit environments. Additionally, the high costs associated with implementing, operating, and maintaining deep borehole seismic networks, which are most commonly used to monitor large open pits, can be difficult to justify, especially if monitoring benefits are not readily apparent. In this study, we explore the use of a near-surface nodal seismic deployment, which is commonly used in oil and gas exploration, for monitoring open-pit mining-related seismicity on a short-term basis. A deployment of 18 geophones was conducted on the surface in and around the Bingham Canyon Mine, a large open-pit mine near Salt Lake City, Utah, USA, where we find the small seismic array can detect and locate a variety of mining-related seismic sources, even with an extremely simplified velocity model. We outline the process of creating an idealized velocity model, developing a local magnitude scale, and interpreting the observed seismicity. Of note, we analyze a sequence of mining-induced events associated with a known structure on the south pit wall. We conclude with discussion on how surface-based deployments may be used to augment, or in some cases supplant, borehole seismic networks at large open-pit mines depending on monitoring requirements and objectives.

Apr 26, 2022

By R. M. BUCHANAN

The segment of Canadian industry based on smelting of alum in um and manufacture of consumer products is based entirely on imported alumina and bauxite. In the absence of Canadian bauxite deposits, consideration of anorthosite, a less desirable aluminous rock, is being undertaken as one alternative in maintaining assurance of supply. Anorthosites in Canada cover many thousands of square kilometres of the Precambrian Shield. Although compositions vary widely among Canadian anorthosites, many appear to exceed the specified minimum of 25% A I 20 3 in bodies containing more than the required JOO million tonnes. A lthough most Canadian anorthosites are of Precambrian age, one located in British Columbia has been identified as being Middle _Cretaceous.

Jan 1, 1984

By Feida Wu, Yuhang Liu, Huimin Gao, Yuhan Song, Zhi Liu, Zijie Ren

In the process of quartz purification by calcination water quenching, the different expansion rates of gangue minerals and quartz were used to produce cracks or remove fluid inclusions, which is conducive to subsequent purification. However, the role and mechanism of calcination-water quenching are still lacking in research. In this paper, the position of calcinationwater quenching in gangue quartz purification process was adjusted and the removal effect of calcination-water quenching process at different nodes in the process was explored. The results show that the purification effects of grinding-calcinationwater quenching-classification-acid leaching process and grinding-classification-acid leaching-calcination-water quenching process were relatively good. The main reason is that calcined water quenching can make quartz produce cracks, which are more rough. At the same time, calcined water quenching is located after grinding, which has a larger specific surface area, pore volume and pore diameter, and has a strong adsorption capacity for acid solutions.

Nov 2, 2023

By Dairo E. Chaverra, Carlos Argumedo‑Jimenez, Oscar J. Restrepo‑Baena

This paper presents the results obtained by processing a gold and silver telluride mineral concentrate from a mine in Colombia. An acid wash, also known as acidification, was carried out, followed by oxidation with nitric acid as a pretreatment. Cyanidations of the pretreatment residues were carried out and the results were compared with results from cyanidations of base materials. The removal of carbonates in the acidification, a tellurium extraction close to 90% during the pretreatment, and a 30% improvement in the gold recovery compared to the conventional process were achieved.

Nov 8, 2023

By M. Moats, I. E. Paschalidou, K. Awuah-Offei

Tellurium (Te) is a rare metalloid that is predominantly produced from the treatment of anode slimes formed during copper (Cu) electrolytic refining. The US Government lists Te as one of the 50 critical minerals, partly, because of its use in thin-film photovoltaic (PV) technology. Given policy initiatives to increase Te production, it is important to evaluate the life-cycle environmental impacts of Te recovery as a by-product of Cu processing. The literature contains a few specific life cycle assessment (LCA) studies of groups of metals that include Te without proper regard to impacts per life-cycle stage of Te production or the effect of allocation on the results. This study builds an LCA model of the production system of Te from anode slimes treatment to evaluate the effect of allocation on life-cycle impacts. We build life cycle inventories using data from the Ecoinvent v3.7.1 database, literature, and engineering calculations and allocate impacts in proportion to products’ mass and economic value. The results show that economic value-based allocation yields greater impacts than mass-based allocation indicating the significant effect of the allocation approach on life-cycle impact estimates.

Feb 1, 2023

By Diler Katircioglu-Bayel, Oner Yusuf Toraman, Safak Gokhan Ozkan

One of the most energy-intensive processes for producing submicron range calcite is stirred media mill. In the present work, numerous operating parameters such as solid mass fraction, grinding media size, media filling ratio, and grinding time have been investigated using a vertical type stirred media mill. The results are evaluated on the basis of mean particle size, specific surface area, and specific energy consumption. After conducting this study, optimum experimental conditions found to be as 70% media filling ratio, 25% solid mass fraction, 1 mm grinding media size, and 120 min grinding time. Besides, energy savings up to 22% were achieved with the choice of proper media size.

By S. Makni, R. E. McIvor

Grate discharges historically outnumbered the overflow type of industrial wet ball mills. However, overflow discharge mills now strongly dominate. In order to understand their comparative advantages and disadvantages, Corem carried out a broad review of this topic. Where the data made it possible, the Functional Performance Equation was used to separate circuit classification from mill grinding effects. Batch tests were conducted in a torque-metered mill at different slurry levels. This paper presents the outcome of these investigations, which is a very strong case for the industry to once again consider grate discharges.

Feb 1, 2023

By Eti Purwaningsih, Widi Astuti, Erik Prasetyo

Selective-reductive leaching of manganese from low-grade manganese ore using tannic acid as a reductant in acidic media was demonstrated by XRD, SEM-EDX characterization, and batch leaching studies at room temperature. The pH change in the liquid phase before and after leaching revealed that selectivity of manganese over iron was due to the hydrolysis of iron. The acidity in the liquid phase during leaching was dictated by two mechanisms: proton-consuming reaction (manganese oxide reduction by tannic acid) and proton-producing reaction (ferric ion reduction by tannic acid to produce ferrous ion). Based on the leaching studies, the more prevalent reaction between these two was determined by initial leaching conditions: tannic acid concentration, sulfuric acid concentration, liquid-solid ratio, temperatures, and agitation time. Kinetic studies revealed that maximum recovery was attained within 6-h agitation, which indicated a product layer diffusion process.

By Da-Qiang Cang, Qingde Wang, Wei Wang, Wen-Bin Dai, Min Guo, Yu Li

Utilization of both slag and its heat for hot slag is a great challenge for iron and steel industry. Many methods of hot slag modification for directly converting hot slag into value-added materials were researched in recent years, and waste heat of hot slag could thereby be transformed into inner energy or chemical energy of the materials. In this paper, an experiment of converting hot slag directly into glass ceramics by hot slag modification method was conducted. A cooled modifiers mainly composed of fly ash were firstly heated though a cyclone furnace and then fell into a molten bath to mix with hot steel slag. Half of hot slag was used as raw materials and accordingly about half energy consumption, about 5MJ/kg for melting raw materials was saved in the process compared with that of traditional producing method. Frit quenched from the modified hot slag had a higher basicity of 0.6-0.7 than traditional frits in order to reduce the needed amount of cold modifiers and accordingly utilize more hot slag and its waste heat. Glass ceramics were further prepared from the frit and a heat treatment of one-stage method is more suiter to such frit than that of two-stage method. The glass-ceramics with basicity of 0.6 and heat-treated by one stage method had the best performance with bending strength of 146.46 MPa, Vickers hardness of 6.79 GPa, water absorption rate of below 2% and shrinkage rate of around 10%.

Jan 1, 2015

By Yuhua Wang, Haitao Zheng, Guangli Zhu, Yuehao Zhao, Fushun Yu, Dongfang Lu

"Spodumene, feldspar and quartz possess similar surface properties, which make the difficult to separate spodumene from other silicate minerals by flotation. The differences of crystal structure, surface property and floatability of three minerals were studied by various technical means. The results show that Li-O and Al-O bonds in spodumene structure are not strong and easy to be broken. However, Al-O and Si-O bonds in feldspar and Si-O bond in quartz are very strong and not easy to be broken. High contents of Al and Li on spodumene surface were found by XPS measurements, which is benefit for the adsorption of anionic collector. The surface energies of main cleavage planes of spodumene (110), feldspar (001) and quartz (001) are 1.88 J/m2, 2.97J/m2 and 2.68J/m2, respectively. Hence, the exposed surfaces of feldspar and quartz are not saturated and easy to adsorb OH- ions from solution and cause the lower IEP than spodumene. The contact angles of three minerals in water are lower than 16º, suggesting that the hydrophilicity of three minerals is high, and the order of hydrophilicity is quartz > feldspar >spodumene. Correspondingly, contact angles and flotation recoveries of spodumene are bigger than that of feldspar and quartz in presence of a combined anionic and cationic collector named YOA.INTRODUCTION Flotation technology plays most important role for the recovery of spodumene from pegmatite ore. Generally, spodumene with fresh surface is easy to be floated using soap and oleic acid as collector, and the best flotation pH range is 4.0 to 9.0. However, the flotability of spodumene will become worse when its surface was polluted by slime which produced by the weathering of spodumene and other silicates (Dresler et al. 1998; Moon and Fuerstenau 2003; Menéndez et al. 2004; Yu et al. 2015). In addition, the species of Ca2+, Fe3+, Mg2+ and other metal ions in pulp can not only activate the flotation of spodumene, but also the activation of gangue minerals, and then the flotation selectivity of spodumene from gangue minerals became wores (Wang and Yu 2007; Yu et al. 2014). In order to eliminate the negative effects of slime and metal ions on the flotation of spoddumene, the desliming and long time scrubbing with the addition of NaOH and Na2CO3 were adopted. Usually, NaOH shows the activation for spodumene flotation, and the recovery of spodumene increases with the increase of NaOH dosage. Na2CO3 can eliminate the non selective activation of Ca2+, Fe3+, Mg2+ ions in the pulp, and the concentrate grade of spodumene increases with the increase of Na2CO3 dosage. Anionic collectors such as chelants, hydroxamic acid, oxidized paraffin soap, naphthenic acid and oleic acid were widely used for the flotation of spodumene (Dresler et al. 1998; Moon and Fuerstenau 2003; Menéndez et al. 2004; Yu et al. 2015)."

Jan 1, 2018

By Jamal Rostami, Omid Frough, Wei Hu

Characterizing the abrasiveness of soil/rock and the allowable wear of hard-facing products in various conditions is a critical factor in selection of the best material for certain applications related to drilling and excavation in mining and construction industries. The Soil Abrasion Index test machine at Colorado School of Mines (CSM) is one of the recently developed unique systems capable of testing soil/crushed rock abrasion under various conditions, such as dry, wet, and saturated settings. It is also capable of testing the performance of various types of hard-facing materials in a given geo-material. This paper studies the wear properties of different hard-facing materials in various crushed rocks from a surface mining operation in the iron range region of the USA. The hard-facing materials include regular and hardened steels and six different specialized hard facings, based on chromium carbide. The soil/rock include a standard sand and two rock samples from the surface mine. Fourteen abrasion tests were conducted, where the weight loss of each hard-facing material was measured over timespans up to 1 h of testing. The results show the distinct performance differences between the steels with 17 HRC and 43 HRC hardness and the hard-facing products for this application. The results show the possibility to evaluate the abrasiveness of different rocks at a mine or construction site and the performance of various hard facings in similar working conditions. This is a practical solution for selection of the cutting tool or reinforcement of bucket lips and truck beds for comparison of relative wear life between different wear-resistant materials.

By Jamal Rostami, Omid Frough, Wei Hu

Characterizing the abrasiveness of soil/rock and the allowable wear of hard-facing products in various conditions is a critical factor in selection of the best material for certain applications related to drilling and excavation in mining and construction industries. The Soil Abrasion Index test machine at Colorado School of Mines (CSM) is one of the recently developed unique systems capable of testing soil/crushed rock abrasion under various conditions, such as dry, wet, and saturated settings. It is also capable of testing the performance of various types of hard-facing materials in a given geo-material. This paper studies the wear properties of different hard-facing materials in various crushed rocks from a surface mining operation in the iron range region of the USA. The hard-facing materials include regular and hardened steels and six different specialized hard facings, based on chromium carbide. The soil/rock include a standard sand and two rock samples from the surface mine. Fourteen abrasion tests were conducted, where the weight loss of each hard-facing material was measured over timespans up to 1 h of testing. The results show the distinct performance differences between the steels with 17 HRC and 43 HRC hardness and the hard-facing products for this application. The results show the possibility to evaluate the abrasiveness of different rocks at a mine or construction site and the performance of various hard facings in similar working conditions. This is a practical solution for selection of the cutting tool or reinforcement of bucket lips and truck beds for comparison of relative wear life between different wear-resistant materials.

By Sam S. Taylor

"INTRODUCTION This report deals with a comparatively simple application of some of the engineering principles involved in the evaluation, installation, and operation of air- or gas-injection projects and well-clean-out and repair methods to increase the producing rates of oil wells in partly depleted pools during the war. The methods suggested for developing gas-injection projects take into consideration that in general no new wells will be drilled because of wartime restrictions of equipment and manpower and that only existing wells and second-hand machinery will be used. Because air will be employed as the injection medium in secondary-recovery operations where natural gas is scarce and expensive, the disadvantages and hazards accompanying, its use are discussed. Engineering techniques recognized as best modern practice are discussed in relation to the effect of simple air-injection development of properties on postwar operations and Probable ultimate recovery of oil. The report is an introduction to where, when, why, and how an air-injection project should be installed and operated; it is not intended to be an engineering manual for technical guidance in the selection, development, and operation of simulative methods of oil recovery.The report is intended mainly for these thousands of operators in the Appalachian region owning a few wells prodding small quantities or oil daily. Many such operators are anxious to increase their production rates by simulative means and to rehabilitate their wells so that they will produce more oil to help win the war but, in general, are unfamiliar with secondary-recovery operations and cannot afford to hire technical assistance."

Sep 1, 1944

By V. S. Papezik

Pyrophyllite, an AI silicate used in the production of ceramic materials, is formed mainly by alteration of felsic to intermediate volcanic rocks, either directly (at temperatures of 250-300°C and pressures of 1-2 kbar) or by subsequent low-grade metamorphism of aluminous protoliths produced by thermal fluids or even by prolonged weathering. Most pyrophyllite deposits in North America are concentrated in a belt of Late Precambrian volcanic and sedimentary rocks, the "Avalon Zone ", which extends along the eastern flank of the Appalachian mountain system from Newfoundland to the southeastern U.S.A. The only producing pyrophyllite mine in Canada is an open pit located near the settlement of Foxtrap on the Avalon Peninsula of Newfoundland. It lies in a belt of rhyolitic flows and pyroclastics intruded by a granitoid pluton. The rocks have been leached along a shear- or fracture zone, depleted in silica, alkalies, Ca, Mg and Fe by the action of hydrothermal fluids, and recrystallized to a very fine-grained massive assemblage of pyrophyllite, muscovite ("sericite") and quartz. High-grade pyrophyllite lenses contain small nodules of diaspore with minor barite; rutile is present in trace amounts. The close proximity of all pyrophyllitized zones on the peninsula to the granite contact suggests that the alteration was produced by thermal fluids genetically connected with the granitoid pluton. The fine-grained pyrophyllite-bearing rocks, with their simple mineralogy, are suitable for quantitative modal analysis by X-ray diffraction. Chemically analyzed samples from the alteration zone were used for the construction of working curves by plotting calculated mineral content against the intensity of selected diffraction peaks. The accuracy of the resulting curves is ±4.5% for quartz, ±3.6% for pyrophyllite and ±2.7% for muscovite. Pelletized samples give best results. The XRD method is suitable for a rapid analysis of a large number of grab or core samples to outline higher-grade areas for more detailed sampling.

Jan 1, 1978

By J. W. R. Rayner

THE conventional method of making water gas involves individual plants for the separate carbonization of coal to coke and the subsequent gasification of coke with steam. The process demands lump coke, preferably made from the best quality of coking coals. The ash in the coke should have a high melting point and the gasification process suffers a loss of efficiency when cokes with low ash-melting points are used. In Britain, these coals are generally the most expensive and they are readily available only in certain localities. The coals not suitable for making lump coke, or yielding only poor quality coke, are much more widely available and are generally cheaper. DEVELOPMENT OF ALTERNATIVE PROCESSES In Germany, processes have been developed and operated commercially for the production of water gas from very low-rank coals such as brown coal and lignites, but much less effort has been spent on processes to use coals of intermediate rank, which are widely available in Britain. The brown-coal processes use coal in the form of either dust or briquettes. The most successful of the dust-gasification methods is the Winkler process, which made a substantial contribution to German oil production during the war. It uses coal in the size range 0 to 8 mm and the fuel bed is blown with a mixture of oxygen and steam at a rate high enough to give it a characteristic boiling motion or, in present-day phraseology, at a rate more than sufficient to fluidize it (Fig. 1). Air cannot be used to provide the heat required for gasification, for vari¬ous reasons. In the first place, to make the process continuous by mixing air and steam would involve the production of a lean gas containing much nitrogen. If a separate blow were used, a large amount of potential heat would be lost because the blow gas in such a process would contain a very high percentage of carbon monoxide. Oxygen is necessary therefore and oxygen remains relatively expensive for use in gasification. In the Winkler generator, formation of clinker caused by local overheating does not occur, because of the mobility and high heat transfer of a fluidized bed. These properties of fluidized dusts have been used most successfully.

Jan 1, 1953

By K G. van den Boogaart, U Mueller

"An accurate prediction of benefit for some types of ore may require not just the ore grade, but a whole compositional characterisation of the estimates; that is, its full mineral composition including waste composition and nuisance elements. An example is Nickel laterite ores, where Ni/Co content must be complemented by estimates of many other elements, as these might have a notable impact on ore processing.Estimates are often obtained with (co-)kriging or co-simulation; however, geostatistics applied to compositional data may yield spurious and inconsistent results because of the constant sum constraint. The log-ratio approach avoids such problems. It proposes a three-step procedure: data are mapped to a set of log ratios of components; for example, the additive log-ratio transformation (alr) transformed scores are modelled with an appropriate fully multivariate geostatistical toolbox; for example, direct/cross-semivariograms and co-kriging or co-simulation results are back-transformed to the original units.Some practical aspects may make the application of this technique difficult: the assumption of Gaussianity and the high dimensionality of the compositions combined with the need for using multivariate methods. This contribution compares several ways of treating compositional data (combining normal score transformation, log-ratio transformations, and minimum/maximum autocorrelation factor (MAF) decomposition) with respect to their ability to generate sensible simulations. The various approaches considered are illustrated with a Nickel laterite data set for which ten variables are available. Both theoretical considerations and illustration results suggest that the best combination is (log)ratio-normal score transform-MAF, in this order. The factors so obtained are closer to Gaussian, approximately spatially decorrelated and can be simulated independently. Simulations can later be recombined to alr-simulations, which in turn may be converted back to point compositions. The resulting simulated compositions are compared with a full Gaussian co-simulation of the raw data. The log-ratio methods show reasonable to good reproduction of mean values, and distribution of the data set and by construction satisfy the total sum constraint, in contrast to the simulations based on raw data for which the total sums fluctuate strongly.CITATION:Mueller, U, Tolosana-Delgado, R and van den Boogaart, K G, 2014. Approaches to the simulation of compositional data – a nickel-laterite comparative case study, in Proceedings Orebody Modelling and Strategic Mine Planning Symposium 2014, pp 61–72 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Nov 24, 2014

By The Staff

"THE property of Red Mountain Mines Limited is located 11/2 miles north and west of the town of Rossland, in southern British Columbia. The mine is situated on the flank of Red mountain, famous in pioneer days as the site of a number of profitable gold-copper producers. Mining and milling commenced in May, 1966, and by the first of July the concentrator was treating close to its average design capacity of 400 tons per day. The following description of the property and its operations is divided into three parts, dealing respectively with geology, mining and milling.GeologyAll the known ore reserves of Red Mountain Mines occur on the Coxey claim, on the west slope of Red mountain. Although there are indications of molybdenite mineralization elsewhere on the Company's property, these have not been developed.The Coxey and adjoining areas are underlain by the Mount Roberts formation of the Rossland volca-nics. This formation consists of an interbedded series of volcanic and sedimentary rocks, mostly brecciated and silicified near the ore zone, and all intruded by igneous rocks which occur in various forms, and vary in composition from basic to acid. The country rock in the vicinity of the mineralization seems to be mostly a volcanic, approximately andesitic in composition, and possibly a surface flow. There is much banding, some of which is undoubtedly due to tuff and agglomerate layers, and some to narrow, siliceous, sedimentary horizons such as the surface exposure of the main ""A"" orebody, much of which was a thin capping of greyish banded rock that looked like quartzite. The drill holes also intersected occasional layers of black, argillaceous quartzite, sometimes altered to a greenish colour. The whole assemblage has been silicified with varied intensity, sometimes to such an extent as to have obscured or obliterated the original characteristics. The mineralized zone has also been strongly brecciated, the fragments varying in size from less than an inch up to large masses, best described as a mega-breccia. Anomalous results obtained in drilling, such as sedimentary sections that do not appear in adjoining holes, may sometimes be due to the presence of these large blocks, no longer in their original position. The whole volcanic unit is thus very complex and confusing. For practical purposes, the ore may be said to occur in a greenstone formation with minor sedimentary interbeds and considerable later igneous material."

Jan 1, 1967

By Frank Ruskey

Many problem associated with potential hazards in a proposed mining area may not be adequately appraised because of the complexity of trying to evaluate them in terms of production requirements. Frequently, encountered hazards have to be dealt with by day-to-day operational schemes that require the miner to either force a way through them or avoid them by blocking off the area in which the hazards are known to exist. These considerations, after the mine is in full production, can be costly to the mine operator and can increase the danger to the miners. A hazard-evasion computer program for mine planning that will appraise proposed mine layouts on the basis of existing or potential hazards has therefore been developed. The program is intended for use during the planning phase of a mine, where it should assist the mining engineer in making decisions in mine design. With the output from this program, the mining engineer should be able either to corroborate his judgments made on the basis of mining experience or to find unanticipated solutions to design problem. The program tests hundreds of possible solutions to a mining layout, and by sorting out the 10 best (based on a criteria of minimum-abandoned-coal) limits the number of choices that need to be considered and appraised for applicability to a given mine scheme.

Jan 1, 1973

By W. V. Swarzenski

In its, effort to combat waterlogging and coil salinity, the later and Soils Investigation Division of WAPDA (West Pakistan's Water and Power Development Authority) has carried out an extensive program of test drilling and water sampling, since 1954. Data collected during the past ten years have permitted the delineation of fresh and saline ground-water-zones in the Punjab Plain. Fresh ground water containing generally, less than 500 ppm (parts per million) of total dissolved solids is found in wide belts paralleling the major rivers and in other areas of fresh-water recharge. Locally, fresh ground water extends to depths of 1,500 feet and more. Saline ground water occurs downgradient from sources of recharge, particularly in the lower central parts of the interfluvial areas and, presumably, underlies most of the Punjab Plain. The ground waters of the Punjab are characterized by their evolution from calcium, magnesium bicarbonate waters, near sources of recharge, to waters containing a dominant proportion of sodium. The highly mineralized waters of the Punjab are generally of the sodium chloride type, whereas in Dera Ismail Khan District sodium sulfate waters predominate. The pattern of distribution of saline ground-water zones and the observed gradual increase in mineral content, downgradient from sources of recharge, can be explained best by a hypothesis stressing the processes of evaporation from the water table and solution of minerals within the alluvial aquifer.

Jan 1, 1967