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By M. Sokoto, H. Hata, K. Nishina, K. Haiki

Fluoride ions in zinc electrolyte cause corrosion to aluminum cathode plates at zinc electrowinning process, so we have developed an iron compound as a fluoride ion adsorbent used in zinc sulfate solution. The iron compound is synthesized from FeC13 solution with a small amount of sulfate ion by neutralizing reaction with Na2CO3 solution. The fluoride ions adsorbed on the surface of the iron compound are desorbed in alkaline solution and the iron compound can be reuse as a fluoride ion adsorbent. Moreover, if adsorption capacity of the iron compound decreases, it can be dissolved in HCl solution and re-synthesized.

Jan 1, 2008

By D. MacGREGOR, VERA TUREK

The St. Canul and Ste. Scholastique orthoquartzite sanrjstone deposits are located within the Potsdam Formation near Montreal. The sandstone lies on Precambrian basement and is Cam/3rian to Ordovician in age. The Potsdam Formation shows two distinct stages of development. One created a deepwater facies represented by impure, limey or shaley sandstone; the other produced a shallow facies composed of grey, highpurity sandstone. The shallow-water orthoquartzitic sandstone at St. Canul is being mined and beneficiated by lndusmin Limited. The operation manufactures a wide range of silica products and supplies industrial areas of Quebec and Ontario with material for the glass, foundry, silicon carbide and ceramic industries.

Jan 1, 1984

By H. E. T. Haultain

Research is a much over-overworked word, sometimes a much abused word; the result of this has been that many who really need the word avoid it, shy away from it just as we do from that most useful word camouflage. We have not been altogether happy in our substitutes. Some years ago I spoilt a very good proposition by using the word investigation. There were those who thought that men and methods were to be investigated instead of simply processes. They expected disruption instead of co-ordination. The bad psychology up-set the scheme. The word experiment is even worse in its psychology. To the mind of the "practical" business man experiment denotes ignorance, waste of time and money and presupposes failure. It is not so long ago that the recognized way of improving the methods about a mine was to get a new manager. Until comparatively recently the average life of a boss in a mine in the West was under, rather than over, two years. Certainly was this the case in the smaller mines. Directors did not recognize that a cock-sure new boss was a greater experiment than a certain amount of feeling-his-way on the part of the old one. We always say that no two mines are the same but we are only now realizing to what extent the fine points of the game can and must be learnt on the job itself. One of the main differences between a small property and a large one lies in this study of the fine points of the game. In the early stages operation is the main point-get her going and keep her going.

Jan 1, 1924

By R. W. Pugh, S. L. Ma

"High carbon rods are typically used as the grinding media in rod mills. Usually an AISI I 090 grade of steel is used which provides the high hardness needed for abrasion resistance and sufficient toughness to prevent rod breakage.Work to improve performance in the past has mainly concentrated on increasing the hardness for improved abrasion resistance. This has been accomplished by adding alloys to the steel which uniformly increase the hardness across the rod section.However uniformly increasing the hardness of the rod produces a more brittle product and at high hardness l1evels can lead to rod breakage problems. Heat treatment processes can be used to selectively increase the surface hardness to high levels while maintaining the core at lower hardness levels to give a product that wears slower without breakage. AltaSteel has developed and mill tested a higher hardness heat treated grinding rodThis paper describes the development of a simple model to predict performance improvement with different hardness profiles and the AltaSteel heat-treated grinding rod process. Mill characteristics of the Endako operation are summarized and predicted performance improvements based on hardmess are compared to the approximate 25% achieved in trials running since July, 1991 at this mill. Early results of other mill trials are also presented.INTRODUCTIONAltaSteel, in Edmonton is a major supplier of grinding media. We have a strong desire to continually increase the quality and performance of our products and thereby improve the efficiency of our customers' processes. In the area of grinding rods, we wanted to produce a product with a significant improvement in wear rate. Second to energy, rod consumption usually represents the next highest cost in processing. This paper presents our development of a heattreated grinding rod that has reduced consumption by about 25% in trials to date."

Jan 1, 1993

By R. B. Harkness

Many of us are familiar with the history of oil in the Province of Ontario, but for the benefit of those who have never heard the story I will repeat it. In 185 7 J. H. Williams, of Hamilton, an old-country Scotchman, who had the advantage of experience gained from the primitive methods used for refining the oil collected at seepages in Roumania, heard of the "gum beds" along Black creek in Enniskillen township, Lambton county. He erected a small plant in the bush and refined illuminating oil, where the village of Old Springs now stands. The labor of collecting this thick ?gummy substance from the sluggish water of the creek, prompted him to dig a well, the next year ( 1858), in the hope of obtaining a greater quantity. When his excavation reached a gravel bed on top of the rock, oil, resembling "lubricating oil of commerce", rose several feet. Several of these wells were dug and his refining business flourished. The following year the Drake well, in Pennsylvania, was drilled into rock, resulting in an oil find which encouraged one James Shaw to make a similar attempt on Black creek. With a spring-pole drill he completed his well in the spring of 1861 to a depth of 160 feet, and at that depth struck a gusher that flowed uncontrolled for several days. Great excitement followed and the village of Oil Springs had a mushroom growth. The Petrolia field was discovered in 1865. Lick followed up the Thames with a spring-pole rig testing the formations along that river and discovered the original Bothwell field in 1865. During the sixties wells were drilled in many counties in southwestern Ontario.

Jan 1, 1924

By M. Pötsch, W. Schubert

"The kinematic analysis of rock blocks is one part of a block stability assessment. It provides information about a block’s movability, i.e. if a block can detach from the adjacent rock mass and move towards the free space. This paper introduces an analytical method for the analysis of pure rotations of arbitrary finite polyhedral blocks. It enables the engineer to judge a block’s rotatability about a corner or an edge. The method is presented using a graphical and computational method. The application of the method is illustrated with an example. INTRODUCTIONThe kinematic analysis of rock blocks deals with the determination of the movability of blocks. Established methods typically cover: (a) translational motion (John 1968, Markland 1972, Londe et al. 1969, 1970, Goodman & Shi 1985, Warburton 1981) and (b) the specific rotational cases Toppling (Goodman & Bray 1977) and Slumping (Kieffer 1998). Mauldon & Goodman (1990, 1996) and Tonon (1998) introduced rotational kinematic analyses for three-joint pyramids and tetrahedral blocks extending Goodman & Shi’s block theory.All mentioned methods are subject to assumptions that limit the applicability to engineering problems. For example, the kinematic test of daylighting joints or intersections inherently assumes a finite block, which only can be proved by the finiteness theorem (Goodman & Shi 1985). Daylighting of an intersection or plane is not a sufficient condition for removability. Goodman & Shi’s and Warburton’s methods are limited to translational block motion. The methods for block rotations so far address tetrahedral blocks only. They also address only pure rotational modes and neglect the general motion of a rigid body. This paper introduces an analytical method for the analysis of the kinematic rotatability of finite rock blocks. It extends Mauldon's and Tonon's theory of rotatability of tetrahedra to arbitrary polyhedral blocks. A graphical method using the stereographic projection and a computational method are presented."

Jan 1, 2015

By O. Moselhi

Material can be seen as the fuel needed to execute the project from inception to completion. Material installed provides good indicators of progress achieved onsite vis-a-vis project schedule performance. It correlates well with the role of the schedule performance index (SPI) of the earned value method (EVM). Material is recognized to have a significant impact on achieved progress for physical completion of project activities. This paper presents a study on the development of material status index (MSI) in support of the EVM. Unlike the SPI, the newly developed index account for the criticality of project activities. This is carried out considering the total float of each activity, percent float (i.e. the ratio of float to activity duration) and the total float of the path on which the activity is located. MSI, can independently and jointly with SPI provide root causes behind problems encountered during project execution. In turn MSI can reveal material related factors behind the performance detected by joint interpretation of the two indices. MSI serves to provide added value in alerting management to take corrective actions. While SPI and MSI may have different values, they can jointly augment and enrich the captured project status based on EVM. To demonstrate the capabilities of the developed MSI method, it is implemented on a case study. The case encompasses the construction schedule of a hydro power station constructed in northern Quebec. Different scenarios are adapted from the real case to demonstrate a set of practical aspects of the developed index. The results generated from the analysis of the case study illustrate the useful features of MSI beyond those of the traditional SPI on two fronts; causation and the considerations of criticalities of actives.

Aug 1, 2013

By W. R. Dodge

THE growth and development of the assay department of the Hollinger Consolidated Gold Mines, Limited, is a similar story to that of the mine itself. As the mine developed and enlarged, so also increased the demands upon this department, necessitating an increase of capacity for fire assaying and a widening of the scope of work to include chemical analysis, metallurgical tests, research, and screen analysis. The yearly total of determinations, taking an average for the past six years, is approximately 350,000. The major portion of this figure represents fire assaying for gold and silver, being approximately 950 fire assays per day. The assay department occupies the ground floor of the administration building and covers approximately 4,000 square feet of floor space. Ready access is had by motor truck and electric railway for the delivery of samples and the removal of crushed rock and rubbish. The combined weight of all sample rejects amounts to about 5,000 lb. per day, which is sent to the mill bins. There are six departments, each occupying a separate room-grinder room, fluxing room, furnace room, parting room, weighing room, and flux-mixing and storage room.

Jan 1, 1931

By T. R. Eger

Miners can be exposed to whole-body vibration (WBV), when sitting or standing to operate mobile equipment. In order to prevent vibration-induced injury it is important to understand how miners can be exposed to vibration, the health risks associated with vibration exposure, methods to evaluate vibration exposure, and strategies to reduce vibration exposure. WBV exposure typically occurs when operating mobile equipment, such as a load-haul-dump vehicle, haulage truck, or dozer. The probability of health effects such as low back pain, neck pain, headaches, and gastrointestinal track problems occurring from daily vibration exposure can be determined based on criterion values published in ISO 2631-1 and EU Directive 2002/44/EC. A special case of WBV termed foot-transmitted vibration (FTV) occurs when a miner is exposed to vibration that travels through the feet. FTV typically occurs when standing on vibrating surfaces associated with the operation of locomotives, jumbo drills, bolters, or raise platforms; however, there is no set standard to evaluate health effects associated with FTV. Recent medical evidence confirms workers exposed to FTV can develop cold induced blanching of the toes, in addition to numbness and tingling in the feet and toes. In order to reduce the risk of adverse health effects from exposure to vibration, the hierarchy of controls (elimination; substitution; engineering; administration; and personal protective equipment) should be followed. Best practices should be used to minimize vibration exposure through equipment purchases (i.e. vehicles with lower vibration emissions and seats that attenuate vibration), reduced driving speeds, and improved road maintenance for example. The elimination of other risk factors, which increase injury risk when combined with WBV exposure, such as awkward working postures, should also be eliminated. Very little is known about FTV exposure therefore further research is required in order to develop exposure standards and identify prevention strategies.

Aug 1, 2013

By T. Tsutsumi, S. Kukino

"During the diametrical compression test, the tensile stress generated near the loading plate is influenced by the contact area between the loading plates and specimen. However, very few studies have determined the contact area. Theoretical or analytical models have shown that for an orthotropic material (i.e., with material properties that differ along each of three mutually orthogonal twofold axes), the maximum tensile stress is generated at the center of disk when the angle of the principal material direction to the loading direction is close to ?/4. The maximum value is almost constant, regardless of the contact area. Conversely, the maximum tensile stress is generated near the loading plate when the angle between the principal material direction and loading direction is small. The maximum value decreases as the contact area increases. Therefore, in the latter case, the influence of the contact area on tensile strength measurement of is significant.In previous studies, the distribution of stresses applied on the loading plate is assumed to be a uniform load. In reality, the applied stress is highest at the center of loading plate and seems to decrease with distance from center. The applied load disappears at the edge of loading plates. In this study, in order to satisfy this boundary condition on the loading plate, the cosine curve is adopted as the distribution of load applied on the loading plates in a theoretical model of the diametrical compression test. Furthermore, the elastic solution using boundary conditions shown in this study is used to obtain the tensile stress distributions on the loading axis for an orthotropic circular plane. These distributions are compared with empirical results obtained under uniform loading with a loading plate or concentrated loading in previous studies."

Jan 1, 2015

By Chester J. Kuryliw

"The Geology of the Cochenour Willans mine, Red Lake district, was described by J. P. Nowlan in the Jubilee Volume. The complexity and intense alteration of the rocks obscured any clear relationship between ore and structure, and Nowlan recognized that future work might greatly modify the ideas then existing. This has proved to be the case. Subsequent detailed work has established the stratigraphic sequence in the Keewatin formations which are the host rocks of the orebodies, and has shown that the principal orebodies are confined to two adjoining bands of tuff.On this basis, it is now possible to map the complex structures with greatly increased accuracy. The amount of drilling and underground exploration required to find new ore has been much reduced, and indicated ore reserves are now substantially greater than at any time in the past. Daily production in 1955 averaged 187 tons per day at 0.578 ounces of gold per ton.The sequence of Precambrian events in the mine area is summarized in the following table:Intrusion of post-ore dykes.Ore formation.Intrusion of post-faulting, pre-ore dykes.Deformation: folding and shearing; alteration; faulting.Timiskaming sedimentation.Unconformity.Keewatin: volcanics and sediments, host rocks of the orebodies, described in detail in the next section.KeewatinFrom oldest to youngest, the Keewatin rocks in the mine area can be divided into six formations, which have been given local names:“Grey"" LavaA fine-grained dacitic to andesitic lava, amygdaloidal and locally containing well formed pillows. Certain areas are sheared and chloritized to a degree that makes identification difficult. The rocks are carbonatized throughout; the most persistent carbonate veins parallel the upper contact. Thickness more than 1,000 feet. (Minor mineralization, type 1 I -See section on Ore Formation)."

Jan 1, 1949

By A. Consigny

New "clean technologies" to treat mining and metallurgical effluents containing dissolved metals have been successfully applied at mine sites in North America and Asia, treating water flows up to 24,000 m3/day. These clean technologies offer significant benefits compared to conventional alternatives and provide a sustainable solution that eliminates residual waste sludge, improves water conservation, generates revenues from wastewater, and delivers overall improvements to the environment. This paper will profile these technologies, and provide best practice case study examples of their application at mining operations, including data for water chemistry, flows, water quality, capital and operating costs, and life cycle costs of treatment.

Jan 1, 2011

By O. Hall

DISCUSSION AT QUEBEC MEETING MR. A. V. CORLETT: With drill holes radiating from a common point, is loading carried to the collars, and do you undertake to distribute the powder evenly? MR. R. V. PORRITT: When the collars of the holes, particularly the diamond-drill holes, are close together, two out of three holes are loaded only to within six or seven feet of the collars, and the intervening holes are loaded close to the collars. When the collars are farther apart, the holes are loaded close to the collars. No spacers are used, and the holes are filled solid with powder, this applying particularly to the diamond-drill holes, except, of course, where the collars are close together and some holes are not loaded close to the collars. MR. J. G. L. McCREA: I would like to enquire in respect to the various efforts made to reduce the cost of diamond drilling to the lowest point, what is. the relative cost of the solid bit to the standard bit? It would seem that the solid bit has the higher cost. MR. PORRITT: The non-coring or solid bit gives a slightly lower diamond cost than the coring bit. With the coring bit, the greatest diamond loss is on the inside stones, apparently due partly to vibration, but mainly to the core blocking against these stones. This condition, of course, does not apply with the non-coring bit. Our experience is that the non-coring bit, which drills out a much greater area, has a diamond consumption slightly less than the coring bit. The non-coring bit is sturdier, and is far less liable to damage in starting holes and in drilling through cracked or broken ground.

Jan 1, 1939

By K. Stankiewicz

Projects as regards state-of-the-art mechatronic systems aiming at increase of safety in the mining industry and at improvement of coal production technologies, which have been completed at the KOMAG Institute of Mining Technology, are presented. These projects cover automation, monitoring and visualization systems, systems for implementation of artificial intelligence techniques, and database recording systems. iRIS system for electronic marking, identification, and recording of components of powered roof supports, which was implemented in 31 Polish mining enterprises, is presented as an example of the work directly associated with an increase of operational safety. Specialists from KOMAG, ELSTA, Ltd., and Silesian University of Technology in Poland, have developed flexible, configurable, and scalable system for data management, which refers to all fixed assets of mining enterprises, meeting the requirements of users as regards marking and identification of fixed assets. The system for control of roadheaders using intelligent algorithms, based on artificial intelligence techniques is also the example of innovative actions. This system aims at increasing the safety and effectiveness of teamwork due to a possibility of remote, semiautonomous operation. Introduction of artificial intelligence technology enables adaptation of roadheader mining system to the present mining-and-geological conditions. Moreover, work aiming at implementation of state-of-the-art system for control of mine jig?s beneficiation node, integrating machines and equipment in one system, is carried out as regards automation, information integration, and visualization in coal beneficiation process. Work on recovery and conversion of thermal energy, which is a by-product during operation of machines and equipment, especially mine diesel drives, is presented. Systems for energy recuperation are more and more important due to the necessity of continuous increase of power production efficiency.

Aug 1, 2013

By M. Askari, M. H. Parsa, S. Kashani-Nejad

Sarcheshmeh refractory consumption rate is about 7.5 - 8 kg/ton of the produced copper, which is almost three times higher than the other smelters practice. High destruction rate of tuyere zone refractory controls vessel productivity and operational lifetime. In this research with the aid of cold model and computational fluid dynamic (CFD), melt recirculation pattern and gas - liquid plume properties in the wide range of gas blowing conditions were studied. Results revealed that in addition to the well-known mechanical refractory destruction mechanism, fast tuyere zone refractory destruction could also be related to the cold bubble cluster formation near tuyere tips and introducing severe thermal shock to the refractory surface. Removing accretion and its strong bonds to the refractories around tuyere tip, causes refractory mechanical destruction and increases tuyere diameter. Increased tuyere diameter, in turn assists gas discharge in the bubbling regime. Air blowing in the bubbling regime result in the formation of big bubble clusters, bubble breakup and back attack occurrence which all found to have major impact on the refractory lifetime. Outcomes of this research, contributed to the plant converting management, blowing hardware and instrumentation improvement.

Jan 1, 2004

By Carl Sonnen

Reading the newspapers, you will know that opposition to ratification on economic grounds always points to the view that action will result in major price increases for energy (to both industry and households) with consequent severe losses of energy production and a loss of competitiveness for energy-intensive producers (i.e., in your kinds of industries). You might think of this as the ?carbon tax? fear, and you should note that many of the initial policy development experiments included variations of this theme. Analysis reported in late 2000 and into early 2002 reported reductions in energy production in the long run of between 10% and 20%. At the upper end of that view, these were the kinds of numbers reported in the Industry Canada study ?leaked? to the Press last week. The consequences of this approach included significantly uneven negative effects for some provinces (e.g., Alberta, but also Saskatchewan and Newfoundland). It had been agreed by the First Ministers of Canada, however, that the policy should not yield those results so development in recent months has focused on eliminating sector and therefore provincial ?sore thumbs?. Although an emissions trading system, which represents this type of approach and directly impacts costs of production, continues to be featured in the new or current policy and is applied to the Minerals Industries among others, it is designed to be implemented in such fashion that the costs are more moderate than before. And because the industries covered by permits are almost all price takers, there is no device for moving an increased price signal forward to ?consumers?. What this does do is even out negative effects among sectors in the economy and for provinces, but at the expense of government financial results.

Nov 1, 2002

By Paul Delottinville, Maynard Hall, Henry Hillier

"An expert system application for supervisory control and optimization of the indurating process at the Iron Ore Company of Canada (IOCC) has been developed and installed in closed-loop. Prior to the installation of the expert system, the indurating machine was rebuilt and the instrumentation revamped. A Foxboro I/A Distributed Control System (DCS) was installed for regulatory control, and a new control strategy configured. The modernization of the regulatory control has resulted in significant improvement in both production rate and product quality. Expert system control was implemented in September 1996. Preliminary indications are that the expert system has further improved the consistency of product quality, enhanced fuel efficiency and increased productivity. The expert system considers both wet and dry sections of the circuit, and its optimization scheme is driven by pellet tumble index and compression strength. Statistical Process Control (SPC) rules were implemented in the expert system as part of the quality analysis and control scheme. The expert system application was developed and delivered using the Comdale Expert Optimizer (CEO), and has been in continuous closed-loop control since its installation. The system development and implementation is described, and preliminary benefits are presented..... IntroductionIn early 1996 the Iron Ore Company of Canada (IOCC) contracted Comdale Technologies of Toronto to develop and implement a real-time expert system for optimizing the indurating pelletizing furnace at our plant location in Labrador City, Newfoundland.The decision to install the expert system has been timely. Like many other resource-based industries in increasingly competitive markets, IOCC recognizes the need to find ways to improve the efficiency of our production process and ensure that product quality is maintained at the highest levels. With the Labrador City plant producing 11 million tons of iron ore pellets annually, implementing the best technology solutions to meet these objectives is critical."

Jan 1, 1998

By G. W. Brooks

This short article is quite different to the general run of papers that are presented to the Institute, but no apology is offered because I consider that first-aid and mine-rescue work are of equal importance to many other subjects that are dealt with in our Transactions. Members of the Institute should be as much interested in the safety of persons engaged in the mining industry as they are in the practical methods of modern mining. We must not only do our best to conserve life and property by adopting every known device to that end, but we must also prepare ourselves so that we may take prompt and effective action when life is in danger, or when property is subject to loss. The need for such preparation in Alberta is perhaps greater than in most places where mining is carried on, and we must spare no effort to assemble at every mine men who are well trained in first-aid and mine-rescue work. The large area over which the mines are distributed renders central training stations out of the question, hence the need for local rescue-teams. Hospitals with skilled staffs, close enough to the mines to be convenient, also seem to be out of the question; therefore the greater need of a high standard of first-aid training for the people in our mining camps. The Government mine-rescue cars are supplied with the equipment necessary for training persons in this essential work and also for dealing with disasters should they occur. The question then arises: are there a sufficient number of men who are trained ? If so we can rest assured that what is possible to be done will be done. But if a sufficient number of trained men are not available much loss of life and damage to property is likely to result.

Jan 1, 1925

By Jocelyn Koshinsky

The uranium milling process at the Key Lake Operation of Cameco in Northern Saskatchewan, Canada results in the leaching of untargeted metal(loid)s such as arsenic, iron and nickel that are found at high concentrations in the ores. To mitigate the environmental impact of the leached As, Fe and Ni in the mill waste solution (raffinate), the pre-discharge mine tailings (rafffinate and residue) are neutralized with slaked lime, resulting in the formation of secondary As-, Fe- and Ni-bearing mineral phases which serve to control their concentrations to very low levels in the tailings porewater. As part of an ongoing investigation into the long-term evolution (10,000 year) of arsenic mineralogy in the Deilmann Tailings Management Facility (DTMF) at Cameco?s Key Lake Operation, it has become necessary to characterize secondary As-bearing mineral phases during the neutralization process prior to the discharge of the tailings and compare these to in situ As-bearing mineral phases in the tailings facility. This is primarily to determine if changes have occurred over time to As-bearing mineral phases in the tailings facility as well as to investigate whether alternate neutralization techniques may have a beneficial effect on the stability of mineral phases formed. Thus a bench-scale model was developed and preliminary testing conducted to simulate the mill neutralization process (i.e. neutralization of synthetic raffinate solutions with incremental amount of slaked lime to terminal pH values). The resulting ?tailings? (precipitates and supernatant) were then separated and analyzed. XRD analysis of the precipitates shows that the Fe occurred mostly as ferrihydrite. This was complimented with results from Raman spectroscopy which further indicated that the As appeared adsorbed onto the ferrihydrite. Results of geochemical modeling of the bench-scale test compared well with supernatant profiles from ICP-MS analysis.

Aug 1, 2010

By William C. Browning

An economic drilling programme is one which costs the !east in chemicals, equipment, and time. The basis for such a programme with rotary drilling techniques is a drilling fluid in which bentonites do not swell. This is recognized in the growing trend toward gyp and other inhibited mud systems. Therefore, even though the mechanism of thinner action is a subject of applied colloid ,chemistry, the understanding of this mechanism is of economic importance in controlling the flow properties of inhibited muds. In phosphate, or sodium tannate, conditioned muds that are relative-!y free of contaminating-electrolytes, the thinner, or dispersing agent, is adsor.bed, ?creating an electrical double layer about the clay particles. The mutual repulsion of these charged particles effects colloidal stabilization, or deflocculation of the suspended clays, as discussed by Norton and others. In inhibited muds, however, the electrolyte concentration in the filtrate is sufficient to collapse the double layer and flocculation of the mud solids occurs, as evidenced by increased viscosity and gel values. Chemicals to control the flow properties of inhibited muds, therefore, are vital to the successful use of these systems as it is not always economical to adjust flow properties by watering back. Flocculation of suspended particles, as indicated in the work of Vervey, Overbeek, and others, is due primarily to gravity-like, long-range Van der Waals forces. Prevention of flocculation may, therefore, be secured by the interposition of any barrier between the particles, the thickness of which approximates the extension of the Van der Waals at-traction. Organic polyelectrolytes, such as Kembreak, Rayf!o, and Q-Broxin, may act to increase the double layer charge when used in small amounts in fresh-water muds. More important, however, is the fact that in inhibited muds an increase in concentration of the polyelecholyte permits the formation of a condensed film adsorption layer of the polyelectrolyte about the clay particle. When this occurs, the extremely viscous condensed adsorption layer creates a mechanical. barrier that prevents flocculation of clays, even in the presence of inhibiting concentrations of elecholytes. Rheological evaluation of the degree of deflocculation, or colloidal stability, may be made by utilizing the known effects of particle inter-action and volume concentration on the flow properties of suspensions. Rheological evaluation should be supplemented by direct microscopic or ultra-microscopic observation.

Jan 1, 1958