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By T. T. Wang, T. H. Huang, S. S. Zhan

"Fractures with diverse features dominate the hydraulic behavior of fractured rocks and are one of the major subjects for hydrogeological characterization of a site. This study investigates curve patterns obtained by packed tests, and as well the influence of fracture features based on 59 sets of in situ packer tests with different fracture combinations and fracture features. The result shows that, in the example of Heshe site, neat and tidy fractures usually provide stable channel for water flow during testing, and the hydraulic properties of fractures infilled with breccia and mud may change during testing because of leaching and/or washed out of infilling breccia and mud. Different combinations of fractures with diverse features in packed test sections lead to different curve patterns for in situ hydrogeological tests. For groundwater flowing predominately through neat and tidy fractures, the pressure-discharge curve of modified Lugeon tests are usually linear curve pattern, and the pressure decrease while the discharge increase in pressure-discharge-time curves of single-hole double packer tests, which benefit statistically determining the transmissivity of dominant fracture sets. INTRODUCTIONFractures interlaced in rock masses are major channels for groundwater flow and generally account for the anisotropic and heterogeneous characteristics of permeability for fracture rocks. To describe reasonably the permeability of a fracture rock, the Discrete Fracture Network (DFN) approach and others with similar ideals have been developed. Many methodologies and associate equipment, for instance, the televiewer and the in situ hydrogeological test, have been proposed to investigate the spatial distribution and the transmissivity for different fracture sets, which are two main parameters necessary for the DFN or similar model simulation (Pearson & Money, 1977; Barker & Black, 1983; Hsieh et al., 1985; Bernard et al., 2006; Quinn et al., 2012). However, diverse outlooks for the pressure-discharge curves and the temporal pressure and associate temporal discharge curves often confuse the investigation results by significant deviations on derived permeability (Houlsby, 1976; Zlotnik, 1994; Royle, 2009; Camilo, 2010).Aiming on technical development for in situ hydrogeological tests and fracture investigation, an experimental well site with 10 wells has been established in Heshe in central Taiwan since 2011 (Wang et al., 2011; Song, 2012; Zhan et al., 2013). Extensive geological survey and well-hole scanning by a televiewer provide spatial distributions and outlooks of fractures in detail. Additionally, a series of Lugeon tests, double packer injection tests and pumping tests have been performed to investigate the permeability of fracture rocks, and dominate fracture sets as well. Based on the results obtained from the Heshe site, this study classifies the curve patterns of hydraulic packer tests. The features of fractures involved in packed sections for packer tests are then inspected in detail. Relationship between the curve patterns of hydraulic packer tests and associated features of corresponding fractures in rock are discussed and addressed accordingly."

Jan 1, 2015

By D. V. Ziehlke, J. M. Franklin, T. M. Gordon, A. G. Galley

The Snow Lake-Wekusko Lake region of northern Manitoba conta ins numerous lode gold occurrences, including the largest gold deposit in the Churchill Prov ince, the Nor Acme mine. The Aphebian volcanic and sedimentary rocks of this region are comprised of submarine volcanic strata, overlain by turbidites, both of the Amisk Group, and fluvi atile sedimenta ry strata and bimodally composed subaerial volcanic rocks of the overlying Missi Group. Gold occurs as: 1) accessory gold in volcanogenic massive sulphide deposits, 2) lode gold in shear zones related to sy n- to post-FI thrust fa ults, and 3) lode-gold associated with post-F2 fault . An alteration a emblage of biotite, al bite and calc ite is associated with both groups of lode-gold deposits, and has been superimposed on the regionall y-developed metamorphic assemblages. AJthough these deposi ts are spatial ly related to britt le-ductile faul ts of different initial ages, they appear to have all fo rmed after the major period of reg ional fo lding and metamorphism, and thus may be penecontemporaneous. The alteration is different from the sericite-ankerite-quartz assemblage that is typically associated with gold deposits in Superio r Prov ince. Deposits in thi s area of Churchill Prov ince may have formed either at a higher temperature or a deeper structu ra l level than tho e in Superior Prov ince.

Jan 1, 1986

By Xing-Liang Sun, Xian-Min Han, Zheng-Guo Zhu

The study on the material properties of frozen soils in China was being developed quickly in the past decades of years, because of the increase of the engineering constructed in frozen soil regions on the Qinghai–Tibet Plateau, and numerous research results were achieved mainly about strength and deformation behaviour and constitutive models of frozen soils. Studies have shown that the deformation procedure of frozen soils is irreversible; therefore, it is more appropriate to research mechanical properties of frozen soils by means of damage mechanics theory. In this paper, an elasto-viscoplastic anisotropic damage model is presented by introduction of Perzyna viscoplastic equation into analyzing the deformation of frozen soil. In addition, an anisotropic damage evolution equation is obtained by means of extending non-viscous damage to viscous damage. Triaxial tests at different strain rates are chosen to illustrate the application of this model, and good agreement between experimental data and numerically simulated results is obtained. The calculated results indicate that, under the same conditions, the damage at higher strain rate is less than that at low one. So the phenomena are explained from damage mechanics that the frozen soil has larger elastic modulus and shear strength at higher strain rates, and explained from mechanism that the emergence and development of micro-cracks in the body of frozen soil can be to some extent retarded at higher strain rates.

Jan 1, 2015

By M. Board, R. Pakalnis, S. Seldon, R. Brummer

The Kidd operation mines roughly 10 000 tpd of copper and zinc ore from underground and employs about 700 personnel. In the late summer and fall of 1997, major movements in the proximity of the east wall of the Kidd open pit had been observed. The Kidd pit had been mined from 1965 to 1977 to depths of 260 m (850 ft), followed by subsequent mining by underground methods to current depths in excess of 1830 m (6800 ft). The No. 1 Mine (2600 Level to pit bottom) is approximately 90% extracted, with most of the remaining reserve between 2000 and 2500 levels. Although initial concerns centred on the stability of the pit walls, the potential ramifications of the movements to the underground were recognized and measures were implemented to ensure the safety of personnel as well as to minimize the potential damage to existing operations. In late October, damage to underground operations was observed as deep as the 2000 Level. In the final assessment, the global mobilized mass was a “wedge”-shaped hangingwall block extending from surface to about 610 m (2000 ft) below surface. The “wedge” boundaries are defined by a fault and shear zone which have continuous lengths in excess of 1070 m (3500 ft); its base by shearing through the host rock mass; and its eastern face by deep tension cracks (Fig. 1). Mined and filled excavations at the western face of the “wedge” allowed mobilization of a mass in excess of 30 M tonnes. Movements in excess of 75 cm (30 in.) per day were recorded on the surface stations that preceded the complete shutdown of operations on October 29, 1997. The evaluations in the days following the shut-down were centred on mitigation of immediate and future possible negative impacts on infrastructure and mining of the remaining No. 1 Mine reserves while ensuring the safety of the operators. This effort required the rapid assessment of the potential damage of the block movement on underground infrastructure, stope access, drainage and ventilation, as well as airblast potential due to the falling of a large block into the pit near the ventilation intake at the base of the pit. These assessments were presented in a previous paper (Seldon et al., 1999). In total, the lateral movement of the block on the ground surface was over 4.3 m (14 ft). This paper describes the detailed studies performed to understand the failure mechanism and to assess the impacts on future mining in No. 1 Mine.

Jan 1, 2000

By J. D. T. Steyl

"This paper presents a phenomenological model of the rate of iron(III) precipitation in batch and continuous autoclaves at medium temperature operating conditions. The rate expressions are based on information obtained from the literature and experimentation at low and high pulp densities. Special allowance is made for the formation of surface nuclei, which appears to be promoted at a higher iron(III) precipitate surface area, especially in suspensions of lower terminal acidity. This leads to the formation of secondary particulates and provides the required link to simulate high pulp density leaching-precipitation systems, using low pulp density batch precipitation data. In particular, the model allows direct application of the simulation to the autoclave oxidation of iron-containing copper sulfide concentrates and provides a good estimation of the relative precipitation rate of hematite, the preferred product, compared to hydronium jarosite. Some interesting mechanistic understandings of iron(III) precipitation in autoclaves are further elucidated.INTRODUCTIONThe objective of this work is to describe the rate of iron(III) precipitation and the relative amounts of hematite compared to hydronium jarosite precipitation during batch and continuous chalcopyrite oxidation under medium temperature (MT) (~130 to 160ºC) autoclave conditions. Published information has not yet revealed sufficient mechanistic insights about this sparingly soluble salt system under these conditions. The rate expressions in this paper are based in part on current literature information, supplemented by qualitative experimental observation at low pulp density conditions, in particular the high-resolution backscatter electron (BSE) images and particle size distributions (PSDs) of the precipitates. A summary of this work and insights from the literature are presented first, after which the behaviour of iron(III) in high pulp density leaching systems is used to derive a phenomenological expression of the effect of existing iron(III) precipitate surface area on the precipitation rate. The overall regression encapsulates all the experimental results, i.e., those obtained in both batch and continuous autoclave configurations (Steyl, 2012a)."

Jan 1, 2012

By G. H. Blackwell, N. I. Norrish

"At most operating mines, geostatistical are reserve estimation methods have been implemented by head office or consulting groups . With recent advances in small computer technology it is now possible for a remotely-located mine department to independently implement a geostatistical package.This paper describes the evolution of geostatistical routines to calculate the mineral inventory for porphyry type copper/ molybdenum or similar are bodies. The problems encountered in down sizing the geostatistical routines to run using limited minesite computing facilities are discussed. The high quality of the results, in spite of some compromises to geostatistical theory, is emphasized.The first stage entailed the development of a mineral inventory based on diamond drill data. The difficulties in fitting variogram models to two metals, copper and molybdenum, and the shortcomings of the mineral inventory due to the mixing of lesser quality exploration data with data from more recent diamond drilling are discussed.To improve the ore reserve estimates for short-term planning, a mineral inventory was produced using both the diamond drill and production blast hole drilling data. This inventory, when compared to actual grades, was found to be quite satisfactory for short-term planning. The inventory also provided a reliable data base for long range pit design and financial planning. By regularly updating the mineral inventory, many of the uncertainties of mining a low-grade orebody were minimizedIntroductionThe comparatively low grades of many Canadian mineral deposit s, the escalation of mine operating costs, and the volatility of metal prices in recent years, has required improvements to both short- and long-term mine planning.One of the prerequisites to improved planning systems is the need for accurate grade prediction. This paper describes the on-site implementation of geostatistical techniques for grade estimation of a porphyry I vein type copper/molybdenum ore body ."

Jan 1, 1987

By D. T. White

Pressure acid leaching of nickel laterite ores typically involves the production of an intermediate product that is releached and refined to pure nickel and cobalt products. BHP Billiton is developing the Ravensthorpe Nickel Project to produce up to 50,000 t/y of nickel via a mixed hydroxide intermediate, which will be refined at its Queensland Nickel (QNI) Yabulu Refinery near Townsville, Queensland. The hydroxide precipitation flowsheet has been adapted to process high magnesium ores through an atmospheric leach stage, eliminate iron(III) as jarosite and oxidise iron(II) during neutralisation. The neutralisation conditions are controlled to precipitate aluminium, chromium and silicon, and to ensure good solid-liquid separation. Soluble impurities such as magnesium are purged with the tailings stream and will be managed over the long term by crystallisation in evaporation ponds.

Jan 1, 2006

By D. D. Bell

This paper presents the history of uranium procurement and demand, and takes a look at future requirements. The three basic conclusions drawn are: (1) the productive capacity of former and existing producers whose operations may be profitably reactivated is insufficient to meet demand projected beyond 1975; (2) reserves in the $5 -$10 price range do not provide the flexibility to sustain production at the high rates required in the late 1970's; and (3) only higher prices can overcome these deficiencies, as this would provide sufficient inducement for the industry to explore for and develop new reserves and productive capacity.

Jan 1, 1967

By W. T. Robson

Introduction Ground failure, violent or otherwise, is a problem to be contended with wherever underground operations are carried out. The character and extent of the failure, whether superficial or of more serious proportions, is determined by a number of factors, among which might be mentioned: the depth and dimensions of the underground workings; the types and distribution of wall rocks; structural features of the ore and enclosing rocks; the degree of metamorphism; the dip of the orebody; concentration of mining operations; the rate of mining; the history of the excavations made on the orebody in question. This last factor implies the consideration of such points as the arrangement and distribution of stoping both past and present, the current sequence of scoping, the type and effectiveness of the support used in old and current workings, and the amount and distribution of unmined parts of the lode. With such a variety of conditions, it is only natural that the situation at one place in a mine will not be the same as that obtaining in another part of the same mine and, more than likely, will be quite different in another property.

Jan 1, 1946

By Guangdong Institute of Resources Comprehensive Utilization, Y. H. Tang, H. X. Hu, T. S. Dong, Z. H. Zhang

"A world class rare metals ore deposit in Africa belongs to a massive granite type poly-metallic pyrochlore-niobium resource. Successful project development in realizing the resource is vital to Africa’s economy and pyrochlore processing technology.The ore properties are quite complex due to the presence of varieties of valuable minerals, fine dissemination and intimate association of minerals and the relative abundance of easy-floatable minerals. The separation of pyrochlore from zircon, calcite and mica is generally considered difficult. Whilst studies have previously been conducted by several independent institutions overseas, no satisfactory process has yet been developed to date for the ore deposit—possibly due to the process designed being too complex; high cost of regents; lower performance.Based on process mineralogy study and extensive testwork, the authors have in recent years developed a new technology—“De-slime—Iron-rejection—Zircon (with calcite) and Calcite reverse flotation—Pyrochlore flotation”. The flow-sheet is characterized by ?1prior removal of slimes and iron minerals; ?2 Zircon (with calcite) and Calcite reverse flotation; and ?3Pyrochlore flotation applying new type of chelating collector GYX3 developed by GZRINM in conjunction with selected regulators and depressants.The process involved in the new technology is simple to implement and facilitates stable operation; the flotation reagent regime is easily adaptable; the cost of main reagent is lower largely because it is easy to manufacture and is environmental friendly. Laboratory test results demonstrated that, for raw ore assaying 0.35% Nb2O5, 0.03% Ta2O5 and 0.45% ZrO2, pyrochlore concentrate grade of >35% Nb2O5 could be obtained with >74% recovery. Meanwhile, the Ta2O5 content in pyrochlore concentrate could be recycled, and ZrO2 recovery >50% could be achieved in zircon concentrate assaying ZrO2>63%—significantly improving the technical-economic indicator. These results were verified in pilot trials of 1.44t/d throughput. The paper presents the new technology in whole, summarizes the key factors affecting its performance and discusses in simple terms the mechanism of separation."

Jan 1, 2016

By Guangdong Institute of Resources Comprehensive Utilization, Y. H. Tang, H. X. Hu, T. S. Dong, Z. H. Zhang

"A world class rare metals ore deposit in Africa belongs to a massive granite type poly-metallic pyrochlore-niobium resource. Successful project development in realizing the resource is vital to Africa’s economy and pyrochlore processing technology.The ore properties are quite complex due to the presence of varieties of valuable minerals, fine dissemination and intimate association of minerals and the relative abundance of easy-floatable minerals. The separation of pyrochlore from zircon, calcite and mica is generally considered difficult. Whilst studies have previously been conducted by several independent institutions overseas, no satisfactory process has yet been developed to date for the ore deposit—possibly due to the process designed being too complex; high cost of regents; lower performance.Based on process mineralogy study and extensive testwork, the authors have in recent years developed a new technology—“De-slime—Iron-rejection—Zircon (with calcite) and Calcite reverse flotation—Pyrochlore flotation”. The flow-sheet is characterized by ?1prior removal of slimes and iron minerals; ?2 Zircon (with calcite) and Calcite reverse flotation; and ?3Pyrochlore flotation applying new type of chelating collector GYX3 developed by GZRINM in conjunction with selected regulators and depressants.The process involved in the new technology is simple to implement and facilitates stable operation; the flotation reagent regime is easily adaptable; the cost of main reagent is lower largely because it is easy to manufacture and is environmental friendly. Laboratory test results demonstrated that, for raw ore assaying 0.35% Nb2O5, 0.03% Ta2O5 and 0.45% ZrO2, pyrochlore concentrate grade of >35% Nb2O5 could be obtained with >74% recovery. Meanwhile, the Ta2O5 content in pyrochlore concentrate could be recycled, and ZrO2 recovery >50% could be achieved in zircon concentrate assaying ZrO2>63%—significantly improving the technical-economic indicator. These results were verified in pilot trials of 1.44t/d throughput. The paper presents the new technology in whole, summarizes the key factors affecting its performance and discusses in simple terms the mechanism of separation."

Jan 1, 2016

By W. H. Gross

To pollute means to make impure or unclean. We tend to forget that man defecates, urinates, sweats, expectorates and exhales and in himself is a beastly little pollutor-but then so is Mother Nature! The object of this paper is to try to put what man and nature do into perspective. The facts indicate that although man may sweat a little, Ms. Nature is by for the greatest pollutor of all.

Jan 1, 1979

By A. L. McAllister

"MASSIVE sulphide deposits are found in two areas of New Brunswick, the St. Stephen area and the Bathurst-Newcastle area. In both, the geology in the immediate vicinity of the sulphide bodies is largely inferred from drilling results as outcrop is not plentiful and is, in fact, almost lacking in most places. With few exceptions these deposits have not been explored by underground methods. Consequently much of the. detail on the geology will only become known over a period of years as economic conditions make mining feasible.Much of the information contained in this paper has been supplied directly by company geologists. As a result of the number of contributors, some confusion of nomenclature bas to be anticipated. Cross-sections and plans of the individual deposits are, in most cases, as supplied by the companies concerned. Most of the interpretations are the responsibility of the author."

Jan 1, 1960

By M. Aljarrah

The phase equilibria in the Mg-Al-Ca system was investigated experimentally by differential scanning calorimetry (DSC) and X-ray diffraction (XRD) techniques similarly the Mg-Al-Sr system has been studied using DSC and XRD as well as scanning electron microscopy/energy dispersive spectrometer (SEM/EDS) and quantitative electron probe micro-analysis (EPMA). A new ternary solid solution MgxAl4,xSr was confirmed in Mg-Al-Sr system, which is a substitutional solid solution of Mg atoms in Al4Sr. Maximum solubilities of 21.3 at.% Al in Mg17Sr2 and 11.4 at.% Al in Mg were observed. It was also noticed that Mg38Sr9 dissolved 12.5 at.% Al. In the Mg-Al-Ca ternary system, one of the invariant transformations predicted by thermodynamic modeling was verified experimentally and found to occur at 512°C with composition close to 10.8 at.% Ca, 79.5 at.% Mg and 9.7 at.% Al. A ternary solid solution (Mg,Al)2Ca was confirmed where large solid solubility of Al in Mg2Ca was observed.

Jan 1, 2006

By Rong. G., T. Q. Lin, W. Du

Based on analysis of the evolutionary history of the valley in Baihetan, the mechanism of asymmetrical evolution, gradual migration-incision evolved from left bank to the right, is revealed in Baihetan river valleys. The process of in-situ stress evolution is carried out by using the Universal Distinct Element Code (UDEC). Consequently, the numerical results which indicate the main regulations of that stress field are as follow: (1) The phenomenon termed "high in-situ stress fold" appears in the bottom of the valley. With the maximum principal stress being 28-34 MPa, the stress increases significantly at a vertical depth of approximately 130 m. (2) The in-situ stress presents zonal distribution along the bank slope. It is apparent that the in-situ stress field consists of stress relaxation zone (SRZ), stress concentration zone (SCZ) and original stress zone (OSZ). The horizontal depth of stress relaxation zone varies from the left bank (roughly 200 m) to the right (about 120 m). Furthermore, the stress evolution of the left bank slope is studied. As a result, it is found that asymmetrical erosion contributes to the difference of the in-situ stress distribution as a critical factor, between the left bank and the right. And for an asymmetrical valley, the evolutionary process of in-situ stress field is a circular procedure, which includes the incision of valley, the accumulation of landslides and the migration of valley.

Jan 1, 2015

By Alf Hartling

"Most of the Paleozoic section of the Williston Basin is a thick accumulation of numerous carbonate to evaporite, shallowing upward, cyclic sequences. These sediments were deposited in broad epeiric seas, and the deposition of the evaporite facies marked the final stage of each cycle. Many of the sequences display a pervasive replacement dolomite in the uppermost portion of the carbonate units. This secondary dolomitization is, at least in part, an early diagenetic event, synchronous with evaporite deposition.The inception of evaporite precipitation resulted in the seepage of a dense, Mg-rich brine into the underlying sediment. The heavy brine moved down the gentle regional dip displacing the more normal marine interstitial pore fluid and dotomitized the primary calcitic sediments en route. The supply of Mg-ions decreased away from the source, and correspondingly, the degree of dolomitization decreased and larger crystals formed because of slower nucleation at fewer sites.The seepage refluxion of dolomitizing brines gave rise to the frequently observed textural variation of cryptocrys talline, impervious dolomite grading into a finely sucrosic, permeable dolomite down-dip. This diagenetic facies change provides the critical up-dip barrier for potential hydrocarbon reservoirs. The lateral pool boundaries are controlled by either structural relief or a similar diagenetic facies change. The reservoirs are capped by the tight evaporites.Hydrocarbon production is attained from diagenetic traps in the Mississippian Oungre Zone and the Ordovician Red River 'C' Zone . Reservoir creation and the pooling mechanism are the result of dolomitization by the seepage refluxion of dense, Mg-rich brines beneath restricted, hypersaline lagoons. When formulating an exploration/ exploitation program for these oil prone horizons, it is essential to understand the complete geological history in order to establish where the reservoirs will be found and to define the areal extent of each accumulation."

Jan 1, 1984

By Christopher Boys

"Many water inflows in Saskatchewan potash mines are linked to salt anomalies. Potash ore and three anomalies in the PCS Cory potash mine in the Patience Lake Member of the Prairie Evaporite Formation were studied to understand the processes involved in their formation. Another goal was to find geological indicators of the proximity of anomalies. A geological model that relates the potash to the salt anomalies has been developed.Up to five post-burial facies may be recognized. These range from carbonate-mud collapse breccias to bedded sylvinite, and probably result from post-burial leaching. In this model, the same fluids that caused widespread recrystallization and possibly enrichment of the potash salts, started by dissolving huge cavities in the evaporites. The effects of the leaching were highly variable, indicated by selectively preserved delicate laminae and chevron textures, to deformed and totally dissolved salt beds. In at least two major events, Late Devonian and Cretaceous, collapse structures may have acted as conduits for overlying formation waters to cause pervasive leaching and recrystallization of the Prairie Evaporite Formation.Geological indicators of the proximity of an anomaly may include: a change in insoluble seam color from greenish-gray to mottled brown and greenish-gray, unusual local increases in ore grade, large patches (e.g., >200 cm2) of sylvite-poor potash crosscutting units near the top of the ore wne, and drops in topography > 10 m of the marker seams. Anhydrite was more common in an anomaly than in ore. The local abundance of anhydrite in ore may indicate the proximity of some salt anomalies. Once an anomaly has been encountered, indicators of a major collapse feature may include: stretched clay seams, folded beds, small collapse features (1 m to 20 m), numerous washouts, or split clay seams with injected salt. Any number, or none, of these indicators may be found close to a major collapse feature."

Jan 1, 1993

By A. Hynes, T. Skulski, D. Francis

The Archean volcano-sedimentary succession in the LG-3 area has undergone two phases of deformation and has been metamorphosed to upper greenschist and amphibolite facies. Marine, fine-grained sediments and mafic pyroclastics comprise the lowest observed stratigraphic unit. These sediments are overlain by a thick sequence of submarine basalts and minor basaltic andesite. The lavas are characterized by high Al/Al+Si, Ti values, low Mg numbers and flat REE profiles (lOx chondrite). A sedimentary prism of coarse elastics which was deposited close to an exposed plutonic highland, overlie the volcanics. Massive lavas of basaltic andesi te and associated volcano-sediments comprise the uppermost stratigraphic unit. These lavas are characterized by high Mg numbers, Ni, Cr, LREE (lOOx chondrite) but low Ti, Al/Al+Si and HRee. The supracrustal rocks were intruded by tonalites and tonalitic gneisses.

Jan 1, 1984

By W. Blum

Progress made in improving the creep resistance of Mg alloys is reviewed with the emphasis on microstructural interpretation. Experimental results on the increase of creep strain with time at constant stress a measured for limited times and strains are displayed in a transparent form as creep rate-strain diagrams from which the minimum creep rate stress is safely derived. In addition, data on the thermal stress component a derived from high-precision a-reduction tests are reported. Within a simple statistical dislocation model these data allow one to quantify the relation between dislocation velocity v and a . In combination with structure evolution laws this relation serves as a basis for modeling the creep rate. New alloys have distinctly higher creep resistance than AZ91 where precipitation hardening plays a minor role. This is due to hardening by intermetallic phases which may form a continuous skeleton along the grain boundaries (e.g. Ca-alloyed AZ91) and/or submicron-sized precipitates within the grains (MRI230D, Mg-Zn-Ca alloys).

Jan 1, 2006

By Joseph U. Messenger

A method of applying ammonium hydroxide to a drill stem containing hydrogen sulphide gas and hydro-gen-sulphide-bearing oil and water so as to remove the hydrogen sulphide as ammonium sulphide is de-scribed. It was concluded that the method allowed trips with drill pipe filled with sour fluids to be made more safely, more rapidly, and more economically. INTRODUCTION THE DANGER of poisoning rig crews during drill stem tests of sour wells by exposing them to hydrogen sulphide gas is well known in Canada. Concentrations of hydro-gen sulphide in sour gases range from 0 to 40 volume percent. There have been numerous casualties from hydrogen sulphide exposure during drill stem testing. Some have resulted in permanent injuries; in some cases the injuries have been fatal. For example, in Alberta in 1957 there were four deaths and 100 exposures which required medical treatment. These fatalities and injuries indicate the need for a more effective way of handling hydrogen sulphide in oilfield operations.

Jan 1, 1958