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We all live in professional silos û comfort zones, where we talk to like-minded people with the same training, experience and view of the world. We note in passing the existence of other disciplines, but they are tolerated rather than embraced. To the geologist, the metallurgist is a mad scientist conjuring gold out of some foul solution about which the less said the better. To the metallurgist, the geologist is a bearded, self-appointed sage who guesses what is under our feet by sniffing the air, and drives a Land Rover badly. As to the view of mining engineers held by both geologists and metallurgists, this is best left to the imagination. And of course we are all confused by the term æmetallurgistÆ. I am called a metallurgist though my skills are in mineral processing not metal processing, but I canÆt be called a mineralogist because that definition is already taken. *Please note that this is available as an extended abstract only*

Jan 1, 2005

By G. H. Charlewood, J. W. McBean

"One hundred years after being developed, the diamond drill is still an essential tool in mineral exploration. The basic principle is unchanged, but the technique has been revolutionized, particularly in the past fifteen years. The cost of core drilling has not kept pace with the rising cost of living. The price of machinery, supplies and labour in drilling has doubled and trebled since 1946. Some of the techniques which have made it possible to hold the price line are described."

Jan 1, 1967

By Arthur B. Yates

Diamond drilling has advanced and expanded during the past few yean. Along with this increase there has been a marked trend to rely more and more upon drilling for the outlining of ore for reserve purposes. This is especially true underground, where men have not been available for opening up ore by crosscuts, drifts and raises. During the recent heavy call upon known ore reserves, more drilling has been done for exploration and it has become expedient to drill longer lateral holes from underground and deeper holes both from surface and from exploration headings in the mines. Furthermore, these deeper holes have to be drilled closely enough to warrant calculation of "probable" if not "proven" ore, from the results obtained therefrom. Interpretation of diamond-drill results has become more precise and reliable with the growing knowledge and understanding of the geologic structures that control the geometry of ore distribution, and this has broadened the field of usefulness of the drill. All of this has created a necessity and a demand for more accurate control of the hole as to direction, a more precise and reliable method of surveying for position, and a need for better and more complete core recovery, as well as larger cores, to provide an adequate sample. At depth the control becomes more difficult and, at the same time, more important. Control A close study of drilling in various parts of the world for a period of more than 20 years has brought to light one definite rule, practically invariable; namely, that diamond-drill holes tend to deviate into a position normal to any structure existing in the rocks, such as bedding, schistosity, gneissosity, or even parting or jointing— even if the hole is started at almost any angle other than parallel with the structure. It also appears that the better developed the structure is, the more quickly will the hole get into a position perpendicular to it. It has often been said that there is a tendency for holes to "drift" in the direction of rotation. This is obviously untrue, for in a vertical hole the measure of deviation would depend upon the azimuth chosen as zero, and there is an infinite number of choices. It has been proved. however, that in homogeneous rocks there is a tendency for the hole to corkscrew, and that the direction of the spiral is the same as the direction of rotation. This may account for the belief that holes drift in that direction. Some tests have been made using right-hand and left-hand rods, and these show that no matter what the direction of rotation the hole will swing into a position perpendicular to the structure. Methods of Control The foregoing empirical rule may be used as an indirect method of control. If the prevailing structure is known, it may be advantageous to start the hole as nearly normal to it as possible, for the

Jan 1, 1946

By M Ozkayhan, N Arslan

"The Efemçukuru underground mine in western Turkey is an intermediate sulfidation, epithermal gold deposit. The bulk of the mineral resources and all of the mineral reserves lie within the Kestanebeleni (KB) vein system. This system comprises four spatially-distinct mineralised zones: the south ore shoot (SOS), the middle ore shoot (MOS), the north ore shoot (NOS) and the KB north-west ore shoot. Production currently occurs only in the SOS, MOS and NOS zones. The gold mineralisation is very fine grained and occurs as free grains in quartz and carbonate, and as inclusions in sulfide minerals. Gold is recovered as part of a sulfide concentrate by flotation methods. Though hosted in the KB vein, the gold mineralisation is not evenly distributed within the veins. Definition of its occurrence is totally dependent on diamond drilling.Diamond drilling at Efemçukuru is done with its own equipment and staff, all managed by the mine geology group. The process over the mine’s six year production history incorporates continual improvement with an innovative approach by focusing on the following: drill team organisation career development and training product research and effective equipment management cost reduction planning and scheduling of development for drill stations.Over 40 000 metres of mostly BQ size core are drilled annually by three drill rigs at a cost approaching US$35/m.The planning and execution of the drilling pattern depends on the configuration of the ore shoot and the planned mining method. Ore extraction is mainly by drift and fill mining augmented by about 15 per cent longhole stoping. The drilling of a specific area is scheduled to be finished 3 to 8 months prior to mining. This scheduling is sufficient for short-term grade model updates and any needed changes to the planned development or stope sequencing prior to planned production from the stope area.CITATION:Arslan, N and Ozkayhan, M, 2017. Diamond drilling at Efemçukuru gold mine, Turkey – a case study on the benefits of timely and cost-effective drilling to short-term planning, in Proceedings Tenth International Mining Geology Conference 2017, pp 285–290 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Sep 20, 2017

By N. W. Byrne

THE study of diamond drill results at the Lake Athabaska property of Athona Mines, Limited, and the co-ordination of information secured, has demanded extensive application of methods for interpreting true conditions, both structurally and from the point of view of ore outlook. This work was in charge of a capable engineer, who, as the result of exhaustive study of the drill cores, has been able to issue maps and plans exceeding the expectations of the majority of engineers and geologists who visited the field during the past summer (1935); that is, having in view the fact that staking of the property had been completed but a few months beforehand and that geological conditions were practically unknown up to the time drilling began in April. The following pages present an outline of the work of the assay and engineering offices in co-ordinating and interpreting the results of the drilling. The writer desires to acknowledge the suggestions offered by A.P. Beavan, geologist and engineer at Athona Mines, whom he assisted during the drilling campaign, and also the co-operation of the drilling contractor's employees. The geological map, mine plans, and forms accompanying the paper are from the Company's engineering office files.

Jan 1, 1937

By C. H. Hitchcock

History In approaching the subject of diamond-drilling practice, a brief history of the origin and development of the diamond drill may be of interest. The use of black diamonds for boring holes in rock was discovered in 1863 by Rudolph Leschot, a French engineer. In 1864, he employed a diamond bit to bore holes for blasting purposes in the construction of the Mont Cenis tunnel between France and Italy. The method was introduced and developed in the United States in the late sixties. The first deep hole was drilled for coal in 1870, near Pottsville, Penn., by M. C. Bullock. This hole was seven hundred and fifty feet deep. It can be inferred that the diamond drill was introduced into Canada in 1871, when a bore-hole, known as Harper's bore-hole, was drilled for coal at Springhill, Cumberland county, Nova Scotia; and at the old Silver Islet mine, near Port Arthur, the diamond drill was in use as early as 1872. Diamond Drills While M. C. Bullock was developing the diamond drill for exploratory work, the Sullivan Machine Company, of Claremont, N.H., was developing the diamond channelers and gadders for quarry work. These quarry machines were very successful until the high price of black diamonds became prohibitive. In 1878, Albert Ball, chief engineer of the Sullivan Machine Company, designed the Sullivan diamond drill so well known today. The first of these drills went to the Lake Superior iron ranges. After 1880, use of the diamond drill expanded rapidly and spread to all parts of the world where exploratory work was being done. In recent years, the type of diamond drill has not changed much, but better material is going into its construction. Steel castings have replaced cast-iron. Ball and roller bearings are now used instead of brasses and babbits. Gun lubrication has eliminated the oil-can. These improvements make a drill that can be operated for long periods without expense for repairs.

Jan 1, 1933

By L. C. Armstrong

Twice in the past two years and in two widely separated localities-one near Williamsville, Mo., and the other in the Allard Lake district of Quebec- the Contract Drilling Division of the Longyear Company has experienced perplexing difficulties in drilling granitoid igneous rocks. The rocks in both places are characterized by appreciable amounts of feldspar intimately intergrown with quartz particles of microscopic dimensions. The disappointingly slow rate of advance and the exceptionally high bortz loss, obtaining during the life of these two projects, are ascribed largely to the resistance to abrasion of these two minerals when arranged in this intergrown pattern. Whether all intergrowth-bearing igneous rocks would offer extraordinary resistance to bit progress cannot be stated with assurance on the strength of these experiences alone. More data on diamond drilling this sort of material in a number of localities are needed before any generalizations can be made safely.

Jan 1, 1949

By CHARLES HOPPER

In preparing the Steep Rock Lake iron ore body for mining, it was necessary to drain Steep Rock Lake. Using diamond drills, a cut 1800 ft long, 100 ft wide, and maximum depth of 95 ft amounting to 300,000 cu yd of material, was excavated in Greenstone to provide a drainage channel. This was done under the general contractor C. A. Pitts, of Toronto, who in turn employed a diamond drill contractor, Boyles Bros., to do the drilling. The method of excavation was selected be- cause a clean square cut and grade could be maintained in the bottom of the channel. Bootlegged holes would have left blocks of rock in the corners which would have created a situation which would have become progressively worse as the open cut advanced from one side of the ridge to the other.

Jan 1, 1949

By W. F. McKechnie

"Southern Africa is generally thought to be well explored, with only limited potential for major new diamond discoveries. However, Chiadzwa in Zimbabwe and reports of a significant new kimberlite find in Angola are testimony to the dangers attached to an attitude that ‘there is nothing left to find’.Since the major discoveries in the central interior of South Africa in the 1870s, diamond exploration in the region has been led by market and political factors that influence the key exploration drivers of opportunity and value proposition. Unexpected new discoveries by new players always impact on existing producers and, from time to time, denial of opportunity through political or protectionist policies has inhibited investment in exploration.Entrepreneurial exploration appetite in southern Africa will be tempered by the potential value equation and security of investment. Overlaid on this, developments in diamond recovery technologies provide opportunity to reinvigorate current mines and old prospects previously considered too difficult or costly to exploit. Position on the cost curve will remain a key factor for survival in an increasingly competitive environment. IntroductionThe diamond industry in southern Africa boasts a history of 150 years of discovery and mining, forming the cornerstone of development of the core, modern economies at the southern tip of Africa.Since the discovery, in the 1860s and 1870s, of the secondary diamond placers and primary diamond-bearing kimberlite deposits in the central interior of the then Cape Colony and Orange Free State, southern Africa has endured as the pre-eminent diamondproducing region in the world. Notwithstanding periodic competition from significant new discoveries in other parts of the globe and the paucity of recent, new discoveries in the region, its ranking is unlikely to change in the short to medium term.In a geological context the region contains the Kaapvaal-Zimbabwe and Angola-Kasai cratons, identified in terms of Clifford’s rule as areas inherently prospective for diamonds, being underlain by portions of the Earth’s crust that are tectonically stable and older than 1.5 billion years (Clifford, 1992). Although the Democratic Republic of Congo (DRC) would, in a geographic context, be considered to be part of Central Africa, for the purposes of this review it is included in southern Africa since northeast Angola and the adjacent parts of the DRC form part of the same geological terrane and diamond production from both countries needs to be considered together. Historical and current diamond production from the northeastern parts of the DRC around Kisangani is not considered to be significant and its inclusion in the overall numbers for the DRC does not materially affect the overall picture presented here."

Feb 1, 2019

By W. L. Honnold

AS BOTH South Africa and diamond mining are unfamiliar subjects it seems best that on such an occasion as this I should endeavor to reflect the atmosphere of the place and to picture the mines from an industrial rather than from a technical standpoint and, because of long absence, my remarks must necessarily be sketchy and in some particulars not up to date. The preferable route to South Africa is via England, direct steamers from America being inferior as to service and effecting no saving of time. The newer boats are of about 20,000 tons capacity and very comfortable. Seventeen days are required for the voyage and only one stop is made-that at the island of Madiera, three days out. Between Southampton, the port of departure, and Madiera the weather may be warm or cold and the

Jan 1, 1925

By Jarek Jakubec

The new euphoria in diamond exploration brings with it a need to understand the challenges that new projects can face in different stages of the development and risks that the commercial outcomes from the new projects fall short of expectations. In many cases, the problems are related to a poor understanding of the technical risks and a failure to adequately address them during the course of investigation. Failure to evaluate all disciplines to the same level of certainty could lead to a situation where the important issues are only identified late in the project development, resulting in costly delays and financial difficulties. The diamond projects located in Canadian Arctic, with its challenging environmental, geographical, social, political and geological contexts are especially sensitive to the high variability of the outcome. This presentation highlights some of the technical aspects that could be the leading sources of risk in diamond projects and could ultimately result in inappropriate mine designs, reducing the economic outcome.

May 1, 2006

By E. P. Gush

Diamonds, an enigma in a mineral resource sense. Chemically, diamonds are no more than carbon crystals in a cubic system-formed one might add under conditions of great pressure and temperature. They have certain physical properties which are fairly unique. They are very hard, they have a high refractive index, they luminesce, some of them fluoresce, they have a high specific gravity, they don't wet and they are a good conductor of heat. In a way, a rather clinical set of qualities. Of course, these qualities are what give diamonds their use and their beauty. It is on the emotional side that they get complex and stir memories of legends, of beauty, of wealth and romance, of war, happiness, bad luck and curses. It is on the emotional side that the value of a diamond is established, if such a thing is possible. Diamonds are extremely varied, there are more than 5000 categories into which they are sorted, so there is room at each point across the spectrum for their individualities to emerge, and accordingly their attractiveness to each buyer is unique.

Jan 1, 1994

By Langdon T. Mitchell, Karl Ingmarsson

The title is not referring to jewelry; nor is it about diamond core drilling. This article is instead about an emerging application for diamonds, hard rock percussive drilling with diamond drill bits. Diamond’s outstanding wear resistance has long been taken advantage of in core drilling. However, until now diamond has been less successful in hard rock production drilling in the mining and quarry industry.

Jan 1, 1999

By J. J. Brummer

The possibility of diamonds occurring in Canada was first raised by W. H. Hobbs in 1899, who concluded: "that the apex of the fan of diamond distribution probably lies somewhere in the strip of the territory bordering James Bay on the east." This was based on the occurrence of diamonds in surficial sediments at various locations south of the Great Lakes. There are two recorded discoveries of drift diamonds in Ontario: (a) the Peterborough Diamond, 33 carats in size, poorly documented and found sometime before 1920;and (b) the Jarvi Diamond, 0.255 carat, found during 1971 in Sheraton Township near Timmins . Both discoveries were in surficial sediments and their source(s) have not been located. During 1960, Selco Exploration Company Ltd. started a heavy-mineral sample program of river gravels in the James Bay Lowlands of Ontario. This was continued by Canadian Rock Company Ltd. (1962-1963) and the Ontario Division of Mines (1973). The surveys discovered the presence of kimberlite minerals in gravel samples from streams draining the Moose River Basin. A total of 53 pyrope grains, four magnesian ilmenites and one grain of chrome diopside were identified from 32 sample locations. A study of the distribution of these minerals suggested the kimberlite source rocks to be located along the north margin or within the Kapuskasing gravity "high" in the area immediately south of James Bay. The Jarvi Diamond, found on an esker east of Timmins, could well have originated from this area. During 1965, an esker was sampled by the Geological Survey of Canada, and the results attracted attention to the area south of Lake Abitibi. At 9 out of 34 sites sampled along the Munro esker, Lee recorded the presence of pyrope garnets and very minor chrome diopside.

Jan 1, 1978

By B. C. Jago, H. Derbuch

"The Freightrain kimberlite is located on the Brodeur Peninsula, Baffin Island, Nunavut. Twin Mining is exploring the pipe and adjacent land (79 claims/655 km2) using a combination of airborne geophysics, soil sampling, diamond drilling, trenching and bulk sample processing. The pipe originally was discovered by Cominco Limited in 1975, re-evaluated in 1993 by Lumina Investment Corporation, when it was staked as the Zulu pipe, and subsequently covered by three claims in 1998 by Helix Resources who called it Freightrain.The Freightrain pipe coincides with a strong, ovoid-shaped aeromagnetic anomaly. It is the only surface exposure of kimberlite within a 30 km long linear trend of fourteen aeromagnetic anomalies that are up to 600 m in diameter.The pipe is exposed in the crater facies, near the transition into diatreme facies as indicated by the occurrence of pyroclastic kimberlite characterized by abundant olivine macrocrysts, juvenile lapilli and kimberlite autoliths set in a serpentine-calcite matrix. Olivine, Cr-pyrope garnet and chromite are the most abundant macrocrysts; clinopyroxene, ilmenite and phlogopite mica occur in minor to trace amounts. Garnet and chromite harzburgite, garnet lherzolite, garnet-spinel lherzolite and rare eclogite dominate the xenolith population.Garnet and chromite mineral chemistry indicate encouraging diamond prospectivity and that potentially diamondiferous garnet and chromite harzburgite were the principal sources of diamond in the mantle at the time of kimberlite eruption.Single clinopyroxene grains define an ~42 mW/m2 sub-continental geotherm that is rooted in the diamond stability field. This compares to a slightly hotter geotherm (~48 mW/m2) for adjacent Somerset Island kimberlites with an origin in the graphite stability field. This data accords with the general lack of sub-calcic Cr-pyrope garnet, diamond inclusion chromite and diamond in Somerset Island kimberlites."

Jan 1, 2002

By R. B. Hoy, Stanley J. LeFond, Unni H. Rowell, K. Reckling, Derek G. Fullerton

In 1989 natural industrial diamonds counted for 55% of the world's natural diamond production. Australia is currently the leading producer (35%). Zaire is the second largest producer (19%). of what is primarily industrial grade rather than gem grade. Botswana (17%) is third, with the former USSR (15%) fourth, and the Republic of South Africa (8%) fifth. Diamonds are also mined in Angola, Namibia, the Ivory Coast, the Central African Republic, Ghana, Tanzania, Guinea, and other African countries. In the Western Hemisphere, Brazil is the principal producer, with some production from Venezuela and Guyana [(Fig. 1)]. A very small output of diamonds is mined today in India, which was the first source of commercial production. In the United States, efforts at commercial diamond mining have been confined to a small area near Murfreesboro, AR. The first diamond was found in a pipe there in 1906. Small scale trial mining has not, however, proved economical. Since diamonds were first discovered more than 2,000 years ago, only about 380 t have been mined. In order to obtain 1 g (5 metric carats) of diamonds, it is necessary to remove and process approximately 25 t of rock. Recovering this small percentage involves a combination of highly developed techniques in mining and extremely sophisticated processes in diamond recovery. END USES Diamonds are used for two unrelated end uses: gem diamonds are jewels of great beauty, while industrial diamonds are essential materials of modem industry. Although imitation stones are substituted for the gem diamond, none of these matches its properties sufficiently well to offer real competition. Synthetic industrial diamonds are now of a quality and size that permit them to be substituted for natural diamonds in numerous industrial applications. For example, synthetic diamonds are available today in sizes up to 100 stones per carat (1.2 to 1.4 mm). In addition, polycrystalline synthetic diamond inserts, such as De Beers Syndite", General Electric's Compaxa and Stratapax", and Megadiamond's Megapax" have replaced natural diamonds in turning tools, mining and oil drilling bits, and dressing tool applications. Industrial Diamonds The diamond is by far the most important industrial abrasive. As recently as 50 years ago, consumption of industrial diamonds was less than that of gem diamonds, but since that time, industrial use has grown to a position of great dominance. During the six-year period 1929 to 1934, the material produced for industrial use amounted to about 74% by weight of the world's total output of diamonds. In 1989 the percentage of natural industrial diamonds mined in the world was 55%. When synthetic industrial diamonds are added to the natural industrial diamond figures, this percentage becomes 87% of total world diamond production including gems, near gems, industrial, and synthetic stones. The many uses responsible for these significant increases are dependent on the properties of the diamond, including hardness, cleavage, and parting, optical characteristics, presence of sharp points and edges, and capacity for taking and maintaining a high polish. The utilitarian role of the diamond was confined primarily to lapidary products until the industrial revolution, which created the first demand for diamond as an industrial tool. In 1777, a British inventor and instrument maker, Jesse Ramsden, used a diamond to cut a precision screw for an engine that he had invented. The first authentic description of industrial diamonds being set in a saw was recorded in 1854 by a Frenchman, Durnain. Eight years later a Swiss watchmaker, Jean Leschot, developed the first diamond drill bit for use in a hand operated machine, which was employed to drill blastholes in rock. In 1864, diamond bits were put to their severest test up to that time in the construction of the Mont Cenis Tunnel in the Alps. A few years later a steam-powered diamond drill with a speed of 30 rpm was able to penetrate rock at the modest rate of 0.3 m/hr. As the industrial revolution gained momentum on both sides of the Atlantic, metal replaced wood and machines replaced people. Thus the foundation was laid for precision engineering and the recognition of diamonds as an indispensable tool of industry. The next major demand for industrial diamonds came after World War I with the development of cemented carbide cutting tools. Diamond was found to be the most effective medium for finishing and grinding the new ultrahard metal. This discovery rapidly increased the demand for industrial diamonds. The availability of inexpensive diamond material inspired tremendous research into applications. By 1935, the first successful phenol-resin grinding wheel containing diamond had been marketed. Soon afterward, the metal-bonded and vitrified diamond wheels were produced, and, as the matrices and bonds that held the diamond grit in place began to improve, the popularity of diamond grinding wheels grew. The outbreak of World War II, and the accompanying increase in use of hard-metal tools in the munitions industry, increased the demand for industrial diamonds. Since about 1950, the development of ultrahard ceramics, semi- conductor materials, plastics, and exotic metal alloys has further consolidated the diamond's position as an indispensable tool of industry. Only diamond is hard enough to cut these superhard materials with the precision, speed, and economy that industry demands today. Special machines equipped with industrial diamonds are used to remove bumps from concrete runways and highways and to modify highway surfaces in order to prevent skid accidents. Many skids are caused by hydroplaning, a phenomenon that occurs when the roadway is wet. Tires mount a film of water and virtually lose contact with the road surface. Diamond machines cut neat, narrow

Jan 1, 1994

By Arturo Ressi di Cervia

The utilization of diaphragm wall construction in Hong Kong began in 1974 with the construction of the New World Center, the first diaphragm wall job built in the British Colony. That landmark job of which I am presenting a few slides and a schematic description, embodied all of the difficulties and problems which are encountered in the difficult geology of Hong Kong. A small rocky island in the South China Sea, Hong Kong provides one of the finest natural harbors in the world. It is its splendid harbor, coupled with the enterprising attitude of the Hong Kong Chinese and the laissez-fair attitude of the British government which has resulted in the explosive growth of this speck of land soon to revert to the political control of mainland China.

Jan 1, 1993

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 Franz-Werner Gerressen, Manfred Schoepf

"Diaphragm walls are known as underground structural elements commonly used as retention systems for excavation pits and shafts and permanent foundation walls or elements. It can be anticipated that, with the increasing trend of utilizing more and more underground space to accommodate environmental considerations and urban/suburban development, there will be an increasing requirement for diaphragm walling in even more complex conditions. Complex and/or challenging conditions in terms of ground conditions have a major impact in regards of choosing the right tools for excavation purpose. Complex conditions in terms of space limitations, especially for inner city job sites, require specifically adapted solutions for slurry, spoil, reinforcement and concrete handling and the related logistic to ensure smooth production. Furthermore, one focus will be given to the QA/QC topics of the production process. Real time installation control, data transfer and reporting systems become more and more important ensuring the five dimensions of a jobsite. Therefore, the paper will describe the construction method and the sequence of activities required for the construction of diaphragm wall systems with the focus on the cutter technology. It will describe also the main equipment which will be needed to execute these works under the various conditions INTRODUCTION Diaphragm walls are known as underground structural elements commonly used as retention systems for excavation pits and shafts and permanent foundation walls or elements. It can be anticipated that, with the increasing trend of utilizing more and more underground space to accommodate environmental considerations and urban/suburban development, there will be an increasing requirement for diaphragm wall usage in even more difficult conditions. Of course diaphragm wall can also be used as deep groundwater barriers (Cut-Off-Walls). This market has shown that the demand for these types of walls is reaching more and more difficult soil conditions or required depths which are surpassing the current standard. The trench cutter is the most important tool for performing this work. The trench cutter itself is a reverse circulation excavation tool. It consists of a heavy steel frame with two drive gears attached to its bottom end, which rotates in opposite direction around horizontal axis. Cutter wheels are mounted onto the drive gears. As they rotate, the soil beneath the cutter is continuously being broken up, removed, mixed with the bentonite slurry in the trench and moved towards the opening of the pump suction box. The slurry loaded with soil and rock particles is pumped by a centrifugal pump which is located right above the cutter wheels, up through a hose system up to a desanding plant where the slurry is cleaned and returned into the trench."

Jan 1, 2015

By V. L. Eardley-Wilmot

Diatomite as prepared for the market is a fluffy, white powder, remarkably light in weight-it weighs only 10 to 15 pounds per cubic foot, or one-tenth as much as sand. Being extremely porous and inert, it is in large and increasing demand for insulation and filtration purposes, as general filler, and for many other uses. Structure Structurally, diatomite is quite different from any other known commercial material. It is composed of myriads of microscopically small, siliceous shells of diatoms which belong to a group of flowerless aquatic plants called algae. When these plants die, the siliceous remains sink to the bottom of the water and form beds of diatomite. Over 8,000 species of diatoms are known, named, and tabulated. The intricate scroll-work and patterns on many of these are one of the marvels of nature, and yet so small are they that from 40 to 70 million separate diatoms may be contained in one cubic inch of material. However, the size and shape of these diatoms, which vary greatly (compare Figures 5 and 6), have an important bearing on the commercial use of the diatomite. The diatoms in the majority of the known deposits are so typical of that deposit that, after a micro-examination, an expert can usually tell not only from what part of the world, but also from what particular deposit, the sample has come.

Jan 1, 1931