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By Michael Schultz, Gregory Sanders

In 2017, the North Texas Municipal Water District (NTMWD) initiated the design of the Sister Grove Regional Water Resource Recovery Facility (SGRWRRF) to provide additional treatment capacity for future population growth within the Lavon Lake watershed. To provide a discharge location for SGRWRRF approximately 4.5 miles of 2.4- meter (96-inch) internal diameter pipeline will be constructed, including 2.3-kilometer (7,800) feet and 487-meter (1,600 foot) long tunnel segments. This paper will discuss the anticipated geology of the two tunnel segments, selection of the tunnel alignment, the anticipated initial tunnel support requirements and other aspects of the project design

Jun 13, 2021

By W. C. Lacy

It is the responsibility of educators to look ahead and prepare young engineers and scientists to cope with industrial and social problems of the future. We are faced with a review of history as well as prophesy of the future. The mining industry exists in a "bubble" with little interaction or communication with the outside. This isolation must be broken down if the industry is to survive in the U.S. and Canada. The ability to communicate with the general public and public officials is essential. Many changes are occurring that will require readjustments in technology and staffing. Aging population will result in raising retirement and increasing available workforce. This may force shorter working weeks to supply additional jobs. Environmental concerns will likely direct more attention not only to these concerns during mining, but to planning for post-mining land usage. Retraining and up-dating educational programs are required to cope with these changes.

Jan 1, 1994

By Mostafa Benzaazoua, Bruno Bussière, Mukendi Kongolo

The desulphurization process has been proposed over the last few years for acid mine drainage control at certain mines, which generate low to medium grade sulphidic tailings (-3 to +25 wt% S). The environmental sulphur recovery, which means the sulphur to be floated to produce a non-acid generating final tailings, depends mainly on the intrinsic neutralizing potential of the tailings. However, in some cases the sulphur cleaning is complicated by other parameters which affect the flotation probability of the sulphide particles. In this study, a number of tests were conducted with a Hallimond tube and Denver Cell on both pure mineral and mine tailings. To develop a better understanding of the mechanisms of non-selective sulphide flotation, three types of approach were investigated in this work: (i) pure pyrite at progressive milling degrees, (ii) artificial mix of pyrite and quartz at different calibrated granulometry and (iii) same composition tailings with 26 % wt sulphur at progressive milling degrees. The effect of the granulometry on the sulphide flotation was demonstrated both. The results allow us to define a granulometry model, which can then be considered in the whole desulphurization modeling.

Jan 1, 2000

By Ahmet Tezcan, Zeki M. Dogan, Yalçin Kaytaz

Autogenous grinding in Turkey was first applied to quartzite where the mill is grate discharge type with an internal diameter of 2.99 m, having a length of 3.20 m and a capacity of as to 11.0 tons per hour. The second autogenous grinding was applied to a copper ore at Murgul Cakmakkaya Flotation plant of (KBI) Black Sea Copper Works having three mills 26 feet in diameter and 10 feet in length in close circuit with hydrocyclones. Recently, alterations were made in grinding circust by adding pebble mills. Furthermore, rubber liners and lifter bars were introduced pebble extractor and classifier were new features in the primary mills and circulating load was reduced by 20-50 tons per hour. At the end of these charges, capacity of each mill line was increased to 48 tons per hour with a full capacity of more than 9000 tons per day. Thirdly, autogenous grinding has been executed successfully on the slags of Samsun Smelting Plant of (KBI) Black Sea Copper Works with a mill of 20 feet in diameter and 6 feet on length having pebble mill following autogenous grinding.

Jan 1, 1992

By Renee Royer, Allan Punkkinen

As mines progress to ever increasing depth, new challenges are encountered with serious concerns for rock excavations in highly stressed conditions. New procedures have been undertaken or are under way to remove workers from the workface, mitigating risk and exposure to hazardous conditions. Rockbolting crews are at particular risk as they are the first line of defense in the installation of the ground support systems. One such initiative for removal of workers from danger has been with remote bolting. Equipment manufacturers have had the ability to remotely inject resin pneumatically into boreholes for several years, but it has not been recognized as a very effective method due to a variety of complications. This makes the installation of dynamic support system components such as the D-Bolt® increasingly difficult. More recently, hollow-core bolts have become popular providing far more effective installation when installed with pumpable, two component urea-silicate injection resins. Normet has developed high energy dissipation self-drilling dynamic bolts (SDDB®) to meet these challenges. Following several inquiries as to the effectiveness of pumpable resins for use with dynamic support components, Normet Canada performed comprehensive testing of the bolt and resin system at CanmetMINING in Ottawa to dispel or substantiate any preconceived beliefs. Several dynamic and static tests in direct and indirect loading were carried out. Results include tests in shear and early strength UCS of the resin to measure the performance of the SDDB compared with the established D Bolt as an effective dynamic ground support component. Underground field observations, installation methodology and in-situ testing are investigated.

Apr 26, 2022

INTRODUCTION From its beginnings in the first decade of this century, flotation has gradually moved to a predominant role in mineral separation. There are several reasons for this, the continuing trend toward treat¬ment of lower-grade and more finely disseminated ores being the major one. Not only has this been true for sulfide ores to which the process was first applied commercially, but also for most nonsulfide ores as well. A second factor has been the broad applicability of the process with respect to particle size; it is effective from 8 to 10 mesh to below 10m. Finally, more so than for any other separation process, flotation has almost no limitations in separating minerals. Gravity, magnetic, or electrostatic processes are either applicable to particular minerals, or to a restricted number of mineral combinations. Flotation, on the other hand, can utilize the wide range of surface chemical differences among minerals, and an equally wide range of reagents. The recent availability of selective flocculation capabilities on a commercial scale as an adjunct to flotation should remove one of the limitations to the process in the very fine particle range. History Although flotation was anticipated in a 19th century patent to Haynes, its first significant industrial uses were in the early 20th century in Australia. According to Hoover,' the Pottter-Del-prat pro¬cess had a "measure of success" at Broken Hill's Block 14 mine in 1905-1906, and was definitely successful at the BHP Mine, where it produced 80,000 tpy of zinc concentrates. Both the Mineral Separa¬tion and the Elmore processes had early trials in Australia also, with both successes and failures. The first application in the United States was in 1911, when the Hyde process was used by the Butte and Superior Copper Co. on a zinc ore in Montana. By 1916 Hoover could list 46 applications to copper, lead, and zinc ores, mainly in the United States. Ten years later Taggart2 listed almost a thousand patents covering processes and reagents which with few exceptions laid the foundations for modern practice. Included were: sulfidizing of oxides; leach-precip¬itation-flotation; cyanides, sulfites, sulfides, and oxidants for selective depression of sulfides; starch, tannin, and glue as depressants; and xanthates, dithiophosphates, and oleic acid as collectors. Within an¬other 20 years, all of these were in commercial use along with amines for floating silica from phosphates, and synthetic frothers were com¬peting with pine oil and cresylic acid. Flotation machine development followed a different course. Of the 170 patents listed by Taggart in 1927,1 those incorporating film and oil flotation-about a third of the total-were no longer then

Jan 1, 1985

By E. M. Frizzell

Development of mobile crusher systems for surface mining, allowing extension of continuous conveyor haulage systems into the pit, is traced from its introduction to the present. Variations in configurations are reviewed, and the compelling reasons for using mobile crusher systems are explored.

Jan 1, 1983

By Mehmet Guney

[The Atlantis-II-Deep is a hydrothermal mineralization located along the median valley of the Red Sea at a water depth of about 2200 m. Extensive exploration of the metal-rich brine deep revealed a potentially mineable deposit on economic interest consisting of oxides, silicates and sulphides with considerable concentrations of zinc, copper, cadmium and silver. Geostatistics was applied to assess the most likely in-situ vague of the metal potential for economical exploitation. Semi-variograms were constructed to characterize the structure of the regionalized distribution of the geological parameters. Volume grades and thicknesses were determined by the kriging technique, avoiding systematically biased high or low grades, and then block .tonnages were computed. The estimation variances, distribution of errors and histograms of observed and kriged values in each grid Mock were also produced.]

Jan 1, 1983

By S. S. Wang

Dialkyldithiophosphinates are a new class of flotation collectors for base metal sulfide ores. Structurally, they are quite different from the conventional collectors such as mercaptans, xanthates, thionocarbamates and dithiophosphates. Collectors Structures [Mercaptans R-SHS Xanthates R-OCS-M+ Thionocarbamates R-OCNH-R Dithiophosphates 2 R-CCNH-R' Dithiophosphinates (R) 2-PS-M+ ] In the above structural formula, R and R' stand for a hydrocarbon radical, and M+ is an alkali metal or ammonium cation.

Jan 1, 1982

By S. Dixon

The use of warm (40-50°C) solution for the selective elution (pre-strip) of copper cyanide from gold and silver cyanides adsorbed on activated carbon was found to elute +90% of the adsorbed copper compared to the use of ambient (20°C) solution eluting 50-70% of the adsorbed copper. The warm solution pre-strip elution did have higher co-elution of gold (1-4%) and silver (10-18%) with the copper. The use of ambient solution pre-strip elution co-eluted less gold (0.2%) and silver (2%).

Mar 2, 2022

By Naeimeh Shabani, Hamid Mirzaie, Javid Sadeghi, Hoda Jafarizadeh-Malmiri, Afshin Javadi

Iron oxide nanoparticles (Fe3O4 NPs), despite their small size, are stable and have a large surface area that allows for absorption and removal of ions as well as turbidity in a short period of time. Thus, the present study addressed the synthesis and characterization of Fe3O4 NPs synthesized using the co-precipitation method and evaluated their effect on the coagulation process in water treatment. The Fe3O4 NPs characteristics were evaluated as follows: magnetic properties were measured using a vibrating sample magnetometer (VSM), surface area using Brunauer–Emmett–Teller (BET), crystal phase using X-ray diffraction (XRD), and morphology using field emission scanning electron microscopy (FESEM). In addition, the effects of the synthetic Fe3O4 NPs on the turbidity reduction of water in various pH levels were evaluated. The synthesized Fe3O4 NPs were without any impurity in the sizes of 22–32 nm, surface area of 99.6 m2/g, pores’ mean diameter size of approximately 10.6 nm, and maximum magnetic saturation of 66.21 emu/gram (emu/g). Using 0.2 g of synthetic Fe3O4 NPs with an initial turbidity of 17 NTU and pH of 6 could reduce all water turbidity (100%). Considering the cheap and facile production and separation, as well as the possibility to reuse them and reduce the sludge water content, iron oxide Fe3O4 NPs can be effectively used for turbidity reduction in the water treatment process.

Oct 26, 2020

"Above ground, elevated belt conveyors that span more than 200 m (656 ft) between support points can cross valleys, rivers, forests and buildings with a minimal footprint. The cable bridge conveyor (CBC) is a new type of suspension bridge based belt conveyor system that has long spans between support points. It combines a typical belt conveyor and an improved simple suspension bridge to form a conveyor bridge. The improved simple suspension bridge places a widened bridge deck directly on suspended cables, without the need for high truss towers. The benefits include reduced cost and increase aerodynamic stability compared to conventional suspension bridges. The CBC’s compatibility with current belt conveyors allows versatility in application.A belt conveyor is a ubiquitous material handling system. Conveyors can be placed directly on ground or elevated above ground by support structures. Considerations of cost, design, environment, civil work, safety and process requirements are all factors in choosing the ground-based or elevated conveyors (Zhang, 2014). The ground-based conveyor has the lowest structural cost when the conveyor is placed on an existing road. Maintenance access is easy and straightforward. Compared to the groundbased conveyor, the elevated conveyor can cross existing buildings and structures, give passage to traffic beneath the conveyor, has a smaller footprint and requires less civil work to pass mountainous areas. The drawback of the elevated conveyor is higher structural cost, which can be compared with savings in civil work and other benefits. Conventional elevated conveyors are supported by rigid truss-type structures, with a typical span of 15 to 25 m (50 to 82 ft) between concrete support bents or steel trestles. Triangular truss, using steel pipes instead of hot rolled steel sections, is more efficient. The typical span of a triangular truss-supported conveyor is around 30 to 40 m (100 to 130 ft), while the weight is about 10 percent less than conventional box truss with a shorter span (Jennings, 2013).Long-span elevated structures based on suspension bridge is another step forward in increasing the distance between support bents, reaching 100 to 400 m (330 to 1,312 ft) and beyond. The wide distance between the support points of an elevated conveyor offers unique benefits. The conveyor can cross rivers, valleys, highways, forests and other obstacles with minimal footprint and reduced civil work. The versatility from long-span conveyors makes bulk material transportation over previously impossible terrains now a feasible option."

Jan 1, 2014

By J. J. Carlson

An important factor in filtration is the zeta potential of the particles. Since zeta potential is a function of pH, it was hypothesized that adding CO would lower the pH and zeta potential. A reduction in zeta potential should enhance the flocculation and increase the filtration rate. This paper describes the effects CO on the zeta potential of both pure hematite and samples of hematite concentrate from an iron ore processing plant. A significant shift in the zeta potential, as a function of pH, curve was observed. These results point to an alteration of the particles mineralogy, not just a shift in pH.

Jan 1, 2010

By Frederic Souche, Andrew R. Klaetsch, Brian Hann, Nick Goodenow

This paper describes support of excavation (SOE) design and construction for three large diameter shafts excavated through glacial soil and controlled blasting in complex sedimentary rock formations. SOE in soil consists of unreinforced secant pile rings designed to resist lateral pressure in circumferential compression, eliminating costly steel core beam reinforcing. Controlled blasting at the shafts, adits, and tunnels in densely populated neighborhoods requires managing risks to the public, buildings, and utilities. Controlled blasting approaches limited adverse impacts to receptors nearby while achieving adequate production and fragmentation. A site-specific observational approach was used to adjust blasting parameters, limiting the impact on local stakeholders while maintaining daily progress and managing overbreak.

Jun 13, 2023

By Jack S. Watson, Rasika Nimkar, Robert M. Counce, BRADLEY BENNETT, Patrick Zhang

This study level process design represents an economically viable method for extracting thorium dioxide and other rare earth elements from monazite ore. This paper incorporates results from the 2019 capstone project from the honors Design Internship in Green Engineering in Chemical and Biomolecular Engineering. In this activity, senior students in Chemical Engineering at the University of Tennessee (UT) focused on the development and study of a process for the recovery of thorium dioxide and P2O5 from monazite. While not mandated, the process offers rare earth oxides as attractive byproducts. The project focused on recovery of byproducts rather than the creation or addition to waste streams. Additionally, (1) the process economics relied heavily on recovery of rare earth byproducts, (2) thoriumhandling portions of the process could be effectively segregated from rare earth and phosphate handling portions of the process, and (3) thorium and uranium content of waste streams should be carefully managed and eliminated where possible.

May 29, 2020

By Manoj Khandelwal, Minghui Liu, Jian Zhou, Kun Du

The waste rock and tailings backfill into the mined-out areas are the most effective method for solving the environmental pollution and surface disasters for nonferrous metals mines. In practice, the success and availability of backfill operations are dependent on the slurry fluidity and the strength properties of cement backfill. The transport of the slurry through the pipeline to the designated backfilling area relies on its eximious flow properties, while the appropriate strength of the filling body ensures the safe operation of the stope. In this paper, the effects of cement and aggregate types on the slurry fluidity and strength characteristics of cemented backfill are studied in detail, which are often ignored in other pieces of literature. Diffusivity is used as an indicator to evaluate the slurry fluidity. Various slurries whose concentrations ranging from 70%, 73%, 75%, 78%, and 80% are made with different aggregate ratios and cement-sand ratios are tested. It has been shown that slurry fluidity is inversely related to its concentration, but 78% is the “stopping point” for the deterioration of fluidity. The addition of rod-milled sand improves or worsens the cemented backfill (CB) strength depending on the amount of rob-milled sand. The uniaxial compression experiment results on 216 CB specimens produced by different combinations of influencing variables showed that CB specimens made from cement with superior mechanical properties have a higher uniaxial compressive strength (σucs). It has been also found that the effect of aggregate ratio on the CB strength is not singular, but works in conjunction with the curing time and the cement-sand ratio. The longer the curing time and the higher the cement content, the higher the CB’s σucs. To avoid the time-consuming and costly problem of obtaining the strength of the CB from indoor experiments, an SVR model capable of predicting the uniaxial compression strength of CB specimens is proposed, which is optimized by genetic algorithm (GA) and particle swarm optimization (PSO) algorithm. The results of the three performance indexes (MAPE, MSE, and R2) show the superior performance of the GA-SVR and PSO-SVR models and the agreement of the predicted results with the experimental results, which indicate that these two models can accurately predict the σucs of CB.

Feb 3, 2022

By Alan Rhodes

This study is initiated to investigate the efficiency of separation of mineral slimes using electroflotation as compared to that of column and conventional flotation techniques. Important parameters such as collector concentration, pH, current density, aeration rate, etc., have been studied. The results indicate that electroflotation can be used more efficiently in processing rutile slimes (10 µ) under certain operating conditions.

Jan 1, 1982

By Sahendra Ram, Ashok Kumar, Rakesh Kumar, AMIT KUMAR SINGH, Dheeraj Kumar, Arun Kumar Singh, Rajendra Singh

This article offers an examination of a retreat mining method conducted at the Pinoura Mine in India from 2010 to 2017. The method is atypical for coal mines of India’s coalfields. The method executes depillaring in a single pass and does not require the formation of galleries and support installation in splits, thus, reducing the cycle time. A variety of observations are discussed throughout this work and emphasis is placed on field measurements and depillaring under weak roof (RMR = 40–45). This paper discusses design techniques, specifically the estimation of the snook (remnant pillar) size, and important practical observations after the fact. The execution of this method was eventually conducted in eleven panels.

Aug 4, 2020

By P. M. Yavorsky

Using a mine roof simulator press capable of duplicating the expected magnitude of vertical and horizontal forces experienced by underground mine roof supports, load capabilities of some roof support cribbings were measured. Comparative ultimate vertical support strengths are reported for cribs of old and new timber and nonreinforced and steel-fiber-reinforced (SFR) concrete blocks. In terms of load- bearing capability, cribs of new hickory and nonreinforced concrete blocks have about equal strength, and SFR concrete blocks are three times as strong. Wood aged 2 years underground lost 43 pct of its support strength. These data were obtained during the course of the initial familiarization exercise of the complex press.

Jan 1, 1984

By Y. C. Kim

Using an exhaustive data set of Walker Lake, four different kriging techniques plus the inverse distance squared weighting were compared with regards to each one's performance in accurately estimating the block grades. The North-West quadrant of the Walker Lake data area was used because of its extreme variability of values and its distinct contour of the values. There were 1900 exhaustive data points in the selected area from which a total of 121 samples were drawn following the sampling strategy given in Isaaks and Srivastava (1989). The average of 5 x 5 exhaustive data points was treated as the true, known block grade. A total of 780 blocks, each block corresponding to the average of 5x5 exhaustive data points, were then estimated using the 121 sample points. The resulting estimates were then compared with the true known values to determine each technique's prediction performance. For this particular portion of the Walker Lake and for the given sampling strategies used, the obtained results for the global estimation are mixed. For the variable U which is much more variable, the rankings are; 1) Jackknife Kriging (JK), 2) Indicator Kriging (IK), 3) Inverse Distance Square weighting (IDS), 4) Ordinary Kriging (OK), and 5) Log-Jackknife Kriging (LJK). For the variable V, the results are; 1) OK, 2) IK, 3) JK, 4) LJK, and 5) IDS. When we apply several cutoff grades to the estimates to determine the conditional mean grades and tonnage, the above rankings generally get shifted around. Two exceptions to these cases are; a) UK for U and b) IDS for V. These two consistently ranked at the bottom.

Jan 1, 1995