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By James S. Goff, Stephen J. Navin, Wesley W. Moulton

The White River Shale Oil Corporation (WRSOC), as agent for Phillips Petroleum Company, Sohio Shale Oil Company, and Sun Shale Oil Company, is developing a prototype oil shale facility on Federal Lease Tracts Ua and Ub, located in northeastern Utah and known as the White River Shale Project (WRSP). The Ralph M. Parsons Company (Parsons) has been retained as the design engineer/constructor for the project. This paper covers the successful pregrouting of the Bird's Nest Aquifer in conjunction with the sinking of a 9.2-m (30-ft)-diameter shaft and driving of a 3.89-m by 5.64-m (18.5-ft by 12.75-ft) decline. The Bird's Nest Aquifer derives its name from the ellipsidal solution cavities caused by leaching of random-size nacholite nodules. The sodium bicarbonate nodules occur as persistent bands within a matrix of siltstone and marlstone. The team, made up of the owner, engineer/contractor, and subcontractor successfully grouted the shaft down to an inflow of less than 0.06 lps (1 gmp) and the decline down to less than 0.12 lps (2 gpm) by injecting a total of 213.190 kg (470,000 lb) of Celtite Terraseal, 113,400 kg (250,000 lb) of limestone dust, and 41,730 kg (92,000 lb) of cement into the formation.

Jan 1, 1985

By Oliver Bololes

UNDER the able leadership of Samuel H. Dolbear, the Committee on Nonmetallic Minerals furnished a program of sixteen papers comprising three sessions. An outstanding accomplishment in technology presented at the first session by Benjamin L. Miller and C. H. Breerwood is the application of flotation to the purification of limestone used in cement manufacture. In place of selective quarrying to provide high-grade raw material, the quarry-run stone is pulverized and treated in froth flotation cells for removal of free silica and mica. Some advantages are cheaper quarrying, more complete utilization of quarry rock, avoidance of purchasing high calcium stone, lower fuel cost and improvement in the finished cement. Paul M. Tyler presented the general subject of milling methods as applied to nonmetal lies. He pointed out the importance of some of the more recent refinements in ore dressing, and urged the need of a wider appreciation of their possibilities. The gypsum industry of Canada was described by L. H. Cole. Crystal growth during the setting process was illustrated by moving pictures. The Coastal Plain and interior salt

Jan 1, 1935

By C. I. Richman

The E h potential during of a iron reducing bacteria such as Aquaspirillum Magnetotacticum (A.M.) can be predicted by a growth model. It also reflects the adsorption of Fe+2 Cu+2 and Mn +2 ions, that can be incorporated into magnetic material called magnetosomes. The Ferric ion concentration during controlled growth of Thiobacillus Ferrooxidans (T.F.) is a function of the bacteria population curve, while A. M. ferrous ion concentration is a function of the integral of the population curve. Charting of the redox potential of T.F. during batch oxidation of refractory ores such as pyrite and pyrrhotite can be helpful to establishing onset and rate the bulk bio-oxidation rate. The onset of biooxidation is marked by an increase in Fe +3 ions that can be correlated with increased growth due to adsorbed electrons.

Jan 1, 1998

By T. W. Guy

DURING recent years, tremendous strides have been made in the economical use of coal. This has resulted in, and to some extent has been a result of, making the fuel specifications more and more rigid. For this reason, all producers have found it necessary to improve their preparation materially, both as to sizing and the elimination of impurities, either by more effective preparation underground or at the tipple and cleaning plant, or both. This cause and its effect in all producing fields seem likely to continue for several years-at least. The splendid inherent qualities of the Pocahontas and New River coals are known all over the world, but their good reputation is only partly due to inherent qualities, and to natural conditions which generally favor loading coal comparatively free from impurities; it is due in large measure to the care and skill used, either with or without the aid of mechanical devices, to ship products consistently low in ash. The first coal from the West Virginia smokeless fields was mined and shipped near Quinnimont, on New River, in 1871, while the first shipments from the Pocahontas field were in 1883. The development of both fields progressed rapidly. At first activities followed the main lines of the Chesapeake & Ohio and Norfolk & Western railroads, and were extended later as branch lines were built from these roads. The Virginian R. R., about 1907, opened up the Winding Gulf territory, which has since become a large producer of smokeless coals from the Pocahontas and the New River measures.

Jan 1, 1931

By Cecil H. Desch

THE progress of metallurgical practice and the demands made by the engineering industry on our foundries and mills have made the crystalline structure of metals a subject of far more than academic interest. Metals and alloys are made up of crystals. Even if we accept the view, so ably maintained by some metallurgists, that the crystals are separated from one another by an amorphous layer, it remains true that all but a very minute fraction of any metallic mass is crystalline. The conditions which affect the growth of crystals are therefore of importance in metallurgy. It is not only castings whose properties depend on the arrangement of their crystals, for the more we learn of the behavior of forged, rolled and drawn metals, the more certain it becomes that it is profoundly influenced by the size and arrangement of the crystals in the original ingot, deter- mining a structure which may persist in a modified form through a long series of mechanical operations and annealings. This is mainly due to the concentration of much of the impurities in the last portions of the liquid to freeze, so that the boundaries between single crystals or groups of crystals are marked out by a zone of segregated material, differing in properties from the mass, and offering a barrier to diffusion and equalization of composition throughout the whole. The importance of this fact has been fully recognized by steel manufacturers, who have to deal with ingots which are sometimes very large, and are cast at a high temperature, containing impurities which have a marked effect on the properties even when present in very small quantity. For this reason the Iron and Steel Institute has set up a committee to examine the whole question of the heterogeneity of steel ingots,(l)f and a report has been issued, containing an account of the structure of 16 ingots, ranging in weight from 15 cwt. to 172 tons, each of which was sectioned and examined by chemical analysis and by etching. A valuable body of data concerning segregation has thus been collected. The work of the committee is being prosecuted with great activity, and at the same time researches are in progress to determine the physical

Jan 1, 1927

By James L. Oleson, Hunter R. Propsom, Kevan J. R. Ford, Robert D. Henderson, Bob Musgrove

"Kinross’ Fort Knox Gold mine, near Fairbanks, Alaska has successfully implemented two major metallurgical continuous improvement projects resulting in growth of gold production and an extension of mine life. In 2009, Fort Knox produced 263,153 oz of gold at a cash operating cost of $543/oz. In 2010, approximately 63% of the gold will be produced from the CIP circuit, 15% of the gold from the gravity circuit and 22% of the gold from the heap leach.In 2009, a 44,000 ton per day run-of-mine valley fill heap leach facility was constructed and commissioned as a cost effective treatment option for low grade ores to supplement the higher grade mill. The heap leach facility will produce approximately 100,000 ounces of gold per year under severe winter conditions. Heap leach gold recovery, based on test work shows 30% after a 55-day leach cycle, with long term ultimate gold recovery targeted at 65%. The paper presents the heap leach design concepts and production data.Additionally in 2009, installation of a Knelson gravity concentrator unit (XD70) was completed. This together with an Acacia intense leach reactor (AILR) has increased overall mill gold recovery from 79.3% to 80.7%. A manual shaking table gold recovery operation has been replaced by batch intensive cyanidation of the high grade Knelson concentrates. Increased removal of coarse gold and difficult-to-leach gold species from the grinding circuit, via the gravity circuit, has improved gold leach recovery in the conventional whole-ore tank leach CIP circuit. The paper presents plant operating data, showing the improvements over the old flowsheet.Focus on the metallurgical properties of the high grade and low grade end components of the Fort Knox ore has resulted in significant improvement to gold recovery."

Jan 1, 2011

By Blandford C. Burgess

Mica is an orchid among minerals. It is formed in pegmatites, one of the most bizarre of igneous formations, and is exceeded by few other minerals in the perfection it may attain as to size, color, and cleavage. First used for window glazing, as an ornament and article of trade, it has become one of the most essential insulators of electricity, heat, and shock. Most internal combustion engines use mica condensers or capacitors and such machines of war as planes, tanks, and submarines are immobile without it. The original manuscript of this guide was written in April 1943 at the peak of war emergency. It was not used be- cause shortly thereafter a decision was made to buy on a one price basis eliminating differentials for both quality and size. This is now presented with the thought that from the standpoint of preparedness we can only consider an- other war imminent and every effort should he made to set up in usable form the experience gained during the Second World War. Colonial Mica Corp. was set up by Metals Reserve Co. as a wholly owned government agency to encourage production of domestic mica and to purchase it. It soon became the exclusive buying agency for such mica. The writer as Southern Manager called on all the private agencies buying mica to assist in formulating buying policies, methods, and prices.

Jan 1, 1949

With the rapidly growing use of hydraulics in mining equipment, maintenance personnel should be familiar with the various components in hydraulic systems. Hydraulic systems do wear out - the fluids they transport are hot and turbulent, the equipment they power often imposes tremendous pressure pulsations and bending stresses, and the working environment is harsh. Therefore, even though hydraulic hoses are made of remarkably trouble-free components, they do need to be replaced periodically. There must be coupling methods that allow hoses to be replaced without disturbing other components. Couplings must also provide a variety of leak-resistant connections between hoses and other components in the hydraulic circuitry. Threaded Connection and Seals Hydraulic coupling thread ends and sealing arrangements are standardized, with many types available. Their outward appearance varies, but coupling configurations are recognizable by examining threads and seals and comparing them to the examples provided here. Iron Pipe Thread There are two kinds of iron pipe threads normally used in mining equipment circuitry - National Pipe Tapered Thread for Fuels (NPTF) and National Pipe Straight Thread Mechanical Joint (NPSM). The NPTF seal is the engagement of the coupling threads, called thread interference. When tightened, the tapered thread of the male fitting binds into that tapered thread of the female fitting to form a relatively leakproof seal (Fig. 1). In the NPSM seal, there is a 30° angle seat machined into the end of the male NPTF fitting. This seat engages with a mating 30° angle cone on the inside of the female fitting. Female NPSM fittings have straight threads, as opposed to the tapered threads of the NPTF fittings. However, most NPTF solid male fittings also have a 30° angle seat enabling them to be used with NPSM female fittings (Fig. 2). JIC and SAE Fittings Joint Industry Conference (JIC) and Society of Automotive Engineers (SAE) seals are formed by joining two mating, conical metal surfaces. The coupling threads are used to bring and hold these surfaces together to form a leak-resistant seal. A JIC connection is a solid male threaded end, with a 37° machined male nose, mating with a 37° female flare seat. When connected, the mating surfaces are held together by the threads, but the threads do not form the seal. The female seat is created by flaring a tube end or machining the interior surface of a stem to 37°. A female JIC has a swivel nut, allowing the sealing surfaces to be joined together without twisting a hose or twisting the seats against each other (Fig. 3). JIC couplings are frequently used on low, medium, or high pressure hydraulic circuits on mining equipment and machinery. The SAE connection is similar in appearance and sealing characteristics to the JIC system, except the angle of the machined male nose and female flare seat is 45° (Fig. 4). "O" Ring Fittings Seals for "O" ring fittings are formed by compressing an "O" ring against an exposed machined surface on a mounting block or hydraulic component part. The "O" ring must be compatible with the type of hydraulic fluid used (Fig. 5). An "O" ring boss connection is made of a male straight thread

Jan 10, 1983

By Donald Bruce

The three types of specifications which are used for micropile work are: ? Performance Specifications: The contractor is permitted control over certain design and/or construction procedures but must demonstrate to the owner through testing and/or certification that the final product meets the specified performance criteria. This method allows and encourages the contractor to provide a competitive and/or innovative micropile design within the framework of the overall design requirements. The responsibilities for the work are shared between the owner and the contractor. ? Open Specifications: These leave the scope and design of the installation up to the micropile contractor. This method is the most common for securing bids on temporary micropile work. The responsibility for design and performance is clearly placed on the contractor. Open specifications are not recommended for permanent applications. This method allows the contractor to select the most economical micropile system. ? Prescriptive Specification: The Owner describes specific procedures that must be followed, but which may not necessarily describe the objective of the work. When prescriptive specifications are used, the owner is responsible for the proper performance of the system. The contractor is responsible for satisfying the details of the specifications. Performance specifications are the most common and best reflect the challenges and interests of micropile technology and applications.

Jan 1, 2004

By Joint Micropiles Committee

"The three types of specifications which are used for micropile work are: • Performance Specifications: The contractor is permitted control over certain design and/or construction procedures but must demonstrate to the owner through testing and/or certification that the final product meets the specified performance criteria. This method allows and encourages the contractor to provide a competitive and/or innovative micropile design within the framework of the overall design requirements. The responsibilities for the work are shared between the owner and the contractor. • Open Specifications: These leave the scope and design of the installation up to the micropile contractor. This method is the most common for securing bids on temporary micropile work. The responsibility for design and performance is clearly placed on the contractor. Open specifications are not recommended for permanent applications. This method allows the contractor to select the most economical micropile system. • Prescriptive Specification: The Owner describes specific procedures that must be followed, but which may not necessarily describe the objective of the work. When prescriptive specifications are used, the owner is responsible for the proper performance of the system. The contractor is responsible for satisfying the details of the specifications.Performance specifications are the most common and best reflect the challenges and interests of micropile technology and applications.The owner, designer and contractor will together be responsible for the tasks associated with the design, installation, acceptance, and performance of the micropiles. The installation of micropiles requires specialized equipment, techniques, and appropriate workmanship. Not every detail of the work can be specified, and not every potential problem can be anticipated. Therefore, a contractor who has demonstrated experience in micropiles must be selected to execute the work required."

Jan 1, 2004

By P. Linzer, L. M. Linzer

The gravity method is often applied in mining-related scenarios such as geological and mineral exploration, detecting subsurface cavities and voids (“receptacles”) that may become sinkholes, siting of surface structures, fault-mapping, and more. It is also widely applied in geotechnical engineering to map subsurface karst profiles and to detect subsurface cavities, such as can occur in open pit mines. While it is widely acknowledged that, compared with other available geophysical methods, this method is the most applicable to the karst profiling problem, survey geometries applied in the field are often far from optimal. The gravity surveying specifications prescribed in SANS 1936 omit some key requirements for optimal survey outcomes, and this paper is intended to fill those gaps. The authors have seen scopes of work that require only a few measurements over the footprint of a proposed structure, indicating a lack of understanding of the nature of the gravitational field. A single gravity measurement is subject to the camouflaging effects of several influences, many of which can be larger than the anomaly caused by the subsurface density variation itself. Papers in the body of literature show an awareness of the need to map the regional field so that it can be subtracted to unmask the residual gravity anomaly, but rarely do they examine how instrument sensitivity governs the size of detectable anomalies or discuss how a detailed terrain correction can be instrumental for isolating faint targets. This paper aims to explain how to apply the gravity method correctly to mining and geotechnical problems, specifically in the detection of subsurface cavities. It discusses various factors to assist with optimising the acquisition of gravity data and its processing so as to maximise the practical value of gravity surveys.

Sep 1, 2025

"1 INTRODUCTIONThe use of nondestructive testing (NDT) methods to evaluate the integrity of Augered Cast-in-Place (ACIP) and Drilled Displacement (DD) piles has been a subject of significant debate among engineers, contractors and NDT practitioners. This guideline document will illustrate the importance of reviewing all available information in conjunction with the NDT records. ACIP and DD piles have unique properties that must be considered when using a specific NDT method. Any evaluation of the integrity of an ACIP or DD pile must also include a thorough review of the detailed pile installation records and the site specific soil conditions. Long or theoretical descriptions of the methods have not been included in this publication. More detailed information about these NDT methods including their theoretical and historical backgrounds can be found in DFI’s Manual for Non Destructive Testing and Evaluation of Drilled Shafts (2004). Additional information can also be found in the more comprehensive textbook Nondestructive Testing of Deep Foundations by Hertlein and Davis (2006).1.1 PurposeThe intent of this guideline is to provide practical guidance for the proper interpretation of NDT results on ACIP and DD piles. Short descriptions of the main integrity methods available are provided along with several examples of how to use all of the information available to make sound engineering judgments about the results. This publication is a state-of-the-practice guideline to promote accurate engineering evaluations.For engineers inexperienced with NDT, these guidelines provide sufficient background information on NDT methods to help understand the limitations of the testing, assess the results presented to them, and formulate appropriate questions. This is particularly important for engineers charged with the responsibility to determine from those results what, if any, consequences there may be on the performance of the structure under construction."

Jan 1, 2016

By R. H. King

Underground coal mining machinery utilizes portable electric sables, "trailing cables." to obtain power from load centers or distribution boxes. Cables are frequently damaged since mobile equipment, poor lighting, and restricted space are inherent to coal mining operations. Normally, the damage is repaired by splicing--the joining of one or more severed conductors and replacing insulation and jacket. Figure 1 illustrates a typical single conductor splice. Although the repair seems simple, difficulty of the splicing process is exemplified by the many safety hazards and frequent production delays that result from defective splices. Forty-two cable splice related injuries were reported to the U.S. Bureau of Mines in 1972 and 1973. Additionally, 17 splices related fires were reported in the three year period prior to December 1972. Assuming the damaged area is quickly located, an average splice time for a two conductor cable is twenty minutes. Some operators estimate this delay is incurred once per day per operating section. If one ton per minute is averaged throughout the shift, each unit could loose 4800 tons per year from splice delays. An estimated cost for materials and labor to make a splice is $20. The expenditure could result in a $4800 annual cost per section. The estimated expense does not include wages of other personnel waiting for the repair to be completed. Nevertheless, labor and materials cost is minor compared to the income lost from decreased production.

Jan 1, 1975

"1.0 INTRODUCTIONThese Guidelines reflect the state-of-the-practice of the Deep Mixing Method (DMM) in North America. DMM is an in situ mixing process that breaks down the soil structure; injects binders, fillers and reagents into the soil; and blends them with the soil. DMM is also commonly referred to as Soil Mixing. The final properties of the treated soil in situ are a function of the composition of the native soils and groundwater, the binders introduced, the mixing methods and energy, and the conditions and time of curing. Treated soils generally have increased strength and stiffness and/or reduced permeability relative to the native soils.This document addresses DMM performed by rotating single and multiple axis mixing tools, rotating cutter wheels at the end of a rigid kelly bar, or trench mixing using a rotating cutting/mixing chain around the perimeter of a rigid bar. Binder may be injected through low or high energy (velocity) jets.The treated soils created through wet DMM are heterogeneous mixtures of binder, water, soil, and groundwater. Treated soils produced by dry DMM techniques are a mixture of binder, soil, and the water already present in the native soil.DMM applications described in this document include•,Earth retention•,Liquefaction mitigation•,Groundwater seepage control and containment isolation•,Bearing capacity improvement•,Deep foundations•,Mass stabilization and contamination containment•,Embankment, levee and dam strengthening, and stabilization•,Casing replacementThis document was developed to address deep foundations applications. Use of deep mixing for seepage control is not specifically addressed. The reader is referred to documents prepared by the U.S. Army Corps of Engineers for additional information. Shallow soil mixing and the use of DMM for stabilization/solidification of contaminated soils performed at depths less than 10 feet (3 m) are mentioned briefly. Jet grouting is not covered by these guidelines."

Jan 1, 2016

By Bengt H. Fellenius

The design of pile foundations is much more commonly verified by means of a full-scale test, than is the design of other foundation units. The reason is not that our knowledge of pile behavior is more uncertain than our knowledge of other foundation types making the verification necessary, but more that the loads in a structure are more concentrated to single foundations in a structure founded on piles as opposed to structures on footings or mats. Therefore, should a pile cap fail or move, the adverse consequence of this is often drastic, as the piled structure has little freedom to transfer its need for support to other foundation units. Consequently, it becomes important to assure the design of piled foundations. In many, maybe in most instances, the static pile loading test is routine and geared toward determining an at least capacity, only. However, in these times there is an ever increasing liability of the professional, demands for increased economy of the foundation, and frequent lack of the involvement in the test of the experienced old-timer exercising good judgment. Furthermore, modern pile design is leaving the single, simple concept of capacity and requires more information from the test to assist in determining aspects of long-term behavior and settlement. Therefore, even the straight forward, routine static loading test requires improved planning, execution, and analysis.

Jan 1, 1990

By W. P. Barba

IN THE early summer of 1917, it became evident that the then existing sources of supply of guns and gun forgings were totally inadequate for the enormous and rapidly growing requirements of the Ordnance Department of the Army, so arrangements were made with sixteen makers of other products to take up the manufacture of guns and gun forgings. Nine of these makers were required to produce their own steel from the raw materials and convert it into rough machined gun forgings; the others finished and assembled these forgings into completed guns. In December, 1914, four of these makers of steel and rough gun forgings were instructed to manufacture the same amount of the 6-in. and 9.5-in. guns and howitzers. It, therefore, seemed practical .and profitable to assemble these makers into a small group, together with the officers of the Ordnance Department, and provide standard 'equipment in each of the four works for the production of these two types of guns. The advantages of this cooperation were immediately manifested, and there commenced an interchange of shop practice and a free discussion of facilities and methods that covered not only the equipment but the manufacturing processes.

Jan 1, 1920

By D. E. Keeley

Introduction Gunite is a mixture of sand and cement applied to any surface by being shot by compressed air through a nozzle, where it is wetted just before leaving the orifice. The mixture is transported through a hose from a machine called a 'cement-gun'(l). Guniting of rock surfaces has been standard practice at the Mcintyre Porcupine Mines, Limited, for several years. Where used on walls and backs of cross-cuts; shaft stations, and other rock openings, as an air seal, gunite has eliminated the necessity of constant scaling to keep rock from falling from these places, and, under worse conditions, it has been used in place of timber supports. This has been of definite help in reducing costs, promoting safety, and minimizing fire hazards. During the past year guniting has been quite extensively used here in the rock head-works of the new internal shaft, No. 12, sunk from the 3,875-foot level. Gunite is at present being applied to the stations of that shaft well below a mile from the surface. This paper describes the method of guniting as carried out at the McIntyre, and illustrates how, by the adoption of this process, mining problems connected with scaling and loose ground have been completely solved. It is hoped that the information presented may stimulate discussion and assist in the use of gunite in this and other mines. The guniting method of applying cement was first developed by Carl E. Akeley (2), Curator of the Field Museum, Chicago, in 1907, and was exhibited in New York at the Cement Show in 1910. The museum was located in one of the old World's Fair buildings, built of roughcast and in bad repair. Mr. Akeley, who was a man of inventive nature, set about devising means of applying cement to repair the walls. The cement-gun was the result. Mr. Akeley was a taxidermist of note, a sculptor, and also the inventor of the Akeley camera. In his work, he was in the habit of using fast setting materials to build up foundations for statues, etc.

Jan 1, 1934

By D Kahler

Modern gold production from the Gympie Goldfield commenced in 1995 with the first production from the Monkland Mine. The primary ore target was the 2.5 m wide Inglewood Fault ore zone, which was initially mined using traditional narrow-vein shrink stoping. This manuallyintensive mining method allowed the mine to re-open with minimal capital cost, however the trade off was low productivity and high operating costs. As the mine has developed, access through 100-year-old, timber-lined, small shafts, and the high cost of delineating reserves, has restricted modernisation of the operations. In early-2000 a stockwork lode was discovered adjacent to the existing workings with an economic width of 40 m. In order to maximise the benefit of such an orebody, mining needed to be approached in a new way. This paper summarises the many changes implemented at the Monkland Mine, including the necessary cultural change, implementing long-hole stoping, de-bottlenecking and the application of mechanisation. The result has been a significant improvement in safety performance, higher productivity and a more secure future for all those involved in the project.

Jan 1, 2002

By T. R. Lippard

PURE gypsum may be broken down into its constituents as follows: [ ] Standard specifications (ASTM Designation C22-25) state that a material shall not be considered gypsum if it contains less than 64.5 pct by weight of CaS042H2O. Anhydrite, the second calcium sulphate mineral found in nature, may be broken into its constituents as follows: [ ] PROPERTIES OF GYPSUM AND ANHYDRITE Pure gypsum is colorless to white but various impurities change its color to shades of gray, brown, red, or pink. It has a hardness of 2 in the Mohs scale and can be scratched with the fingernail. The specific gravity of pure gypsum is 2.3 to 2.4, so that rock gypsum, free from moisture, weighs about 145 lb per cu ft. Gypsum crystallizes in the monoclinic system in tabular crystals that exhibit good cleavage

Jan 1, 1949

By V. G. Papangelakis, G. A. Moldoveanu

The use of anhydrite (AH) seed, control of acidity levels and ageing were assessed as means to promote the conversion of freshly produced metastable gypsum generated in-situ to the less soluble anhydrite phase and force deposition of calcium sulphate on seed as opposed to on equipment as scale, while achieving lower terminal aqueous calcium concentration as well. It was found that moderate sulphuric acid levels (0.25M) and ageing in the presence of AH seed accelerated the gypsum-AH conversion, achieving 100% transformation of the metastable gypsum generated in situ to the more stable, less soluble AH in 6-7 days, while lower/nil acidity did not promote more than 30% AH conversion for 10 days, even in the presence of AH seed. These findings indicate that anhydrite seeding, ageing and incomplete neutralization are beneficial for scale control as well as achieving lower calcium levels, thus rendering the resulting solution more amenable for recycling.

Jan 1, 2015