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By Dennis S. Kostick

Soda ash is the common name for sodium carbonate (Na2CO3), an alkali compound that is the 11th largest inorganic chemical in terms of production of all domestic inorganic and organic chemicals, excluding petrochemical feedstocks. Despite that most people have never heard of soda ash, it is an important industrial compound used to manufacture glass, chemicals, soaps and detergents, pulp and paper, and many other familiar consumer products. Natural alkalis have been used by mankind for thousands of years; however, their industrial manufacture dates back to only the latter half of the 18th century. Natural deposits of sodium carbonate have been known as early as about 3500 BC, when the Egyptians used natural soda ash in making glass. They also mixed lime and soda ash to make sodium hydroxide (caustic soda) that was combined with silicate minerals found in the Sinai desert. This made a soluble silica, which when added to aluminum-rich silt from the Nile River, produced a silica- aluminate cement mortar with excellent bonding properties for construction. The Romans in the first century AD also used natural soda ash in glass manufacture but expanded its use medically for the treatment of colic pains and skin eruptions, and in the making of bread. Elsewhere, people used the ashes of wood to obtain their source of alkali. People learned over time that different types of wood yielded various ashes with different properties; therefore, various plants were burned specifically for their ashes. Ash from plants grown in salt-bearing soils (such as saltwort) and from kelp and other seaweeds, especially Spanish barilla, were so different from ashes obtained from other vegetation that it became known as soda ash (due to its sodium content) versus pot ash, a potassium-based alkali ash. About 13 t of barilla ashes produced 1 t of sodium carbonate and 14 kg of iodine as a byproduct. The difference between these two ashes was relatively obscure until Duhamel Dumonceau made the distinction clear in 1736. The word soda ash developed from common usage and is perhaps more well known today than its synonym sodium carbonate. One of the primary ores of soda ash is trona, a sodium carbonate-bearing mineral that's name is traced back to Arabic origin. Trona also is known internationally by other names such as urao (Venezuela), kaum (Nigeria), natron (from Greek nitron and Latin natrium), and szekso (Hungary). The beginning of the Industrial Revolution in Western Europe in the late 18th century soon put a strain on the availability of raw materials to meet consumer demands. One of these scarce materials was soda ash. Because of the Seven Years War with England and the Napoleonic wars with other parts of Europe, France could not obtain sufficient quantities of Spanish barilla or other supplies of vegetable alkali to meet the growing demand. Efforts were needed to synthesize soda ash. In 1775, the French Academy of Sciences offered a large prize of 2,400 livres to someone who could find an inexpensive method to make soda ash. In September 1791 at St. Denis, Nicolas Leblanc (1742- 1806), a French chemist, developed such a technique using salt, sulfuric acid, coal, and limestone. The French Revolution interfered with its development, and his patent and factory were confiscated with Leblanc receiving only token compensation. Napoleon returned his factory to him; however, Leblanc was not able to raise enough capital to reopen it, and he committed suicide in 1806. A small, but not particularly successful, Leblanc plant was established in England in 1814. It was not until 1823 when the process first became commercially successful in Liverpool, England. The process was introduced in Germany in 1843 and in Austria in 1851 (Harness and Coons, 1942). Soda ash production by the Leblanc process reached its peak of about 599 500 t in 1880, after which it began to decline as the Solvay process became more popular. The Leblanc process was used to a limited extent in Europe during World War I but had disappeared by World War II. The Solvay process, also known as the ammonia-soda process, was developed by Alfred and Ernest (1 838-1922) Solvay in 1861 based on a concept by Fresnel that had been known since 1811. For the next 50 years, the implementation of the idea evaded industrial chemists because no large-scale and economic means could be found to commercialize the concept. Although Ernest Solvay was unaware of the existance of an ammonia-soda concept, he solved the problems by utilizing carbonating towers. The Solvay process produced soda ash from salt, limestone, and coke, with ammonia as a catalyst. With a capital of 136,000 francs, the first plant was built by the Solvay brothers at Couillet, Belgium, in 1863 with production commencing in 1865. Synthetic soda ash production amounted to 1.5 tpd in 1866, but reached 10 tpd by 1872. They patented their use of carbonating towers in 1872 that had made ammonia-soda manufacturing a successful continuous process. Their second plant was built in 1872 at Dombasle, France. In 1874, the first Solvay plant in England was built at Northwich by Ludwig Mond, the namesake of Brunner Mond and Co. (formerly Imperial Chemical Industries), the company that currently operates the two English Solvay plants. In the United States, William B. Cogswell in February 1879 heard a presentation on the Solvay process and sailed to Europe to meet with the Solvay brothers to seek their support for using their process in New York. At first, the brothers were not interested; however, Mr. Cogswell was persistent and ultimately gained their support. The Solvay Rocess Co. was formed Sep. 2 1, 1881, and construction began immediately on the first Solvay plant at Geddes, near Syracuse, NY. The plant came onstream Jan. 10, 1884, and produced 11 180 t in its first year of operation. In 1910, rotary calciners were installed that increased capacity to 1 000 tpd. By 1930, plant capacity was up to 2 400 tpd. The facility remained in continuous operation for more than 100 years. By 1939. 10 Solvay soda ash plants were in operation in 6 States throughout the nation. The Syracuse plant was officially closed Jan. 6, 1986, with total shutdown completed by Feb. 1986. Ironically, this facility was the first Solvay plant as well as the last. Other than the first Solvay plant beginning in 1884, the majority of US soda ash supplies during the 19th century came from imports. The remainder of the US supply

Jan 1, 1994

By Charles H. Ricker

Simulation models have been widely used to analyze the operations and characteristics of a variety of systems. Such models mimmick a projected reality by analyzing the interaction of the events, transactions, and facilities which combine to make up the system. The models are structured as a computer representation of the system components and their logical, precedence and timing relationships. The operation of the system is then simulated over some finite time interval to gather analytical and staistical data. This paper presents a method whereby bulk handling systems, either actual or proposed, may be analyzed by means of simulation models to project the enconomic consequences which may be expected from the system over some future time interval. An example is given to illustrate the construction of bulk handling simulation models, the derivation of performance data, and the analysis of the information with an eye to effective decision making.

Jan 1, 1974

By Michael J. Humenick

A laboratory experimental research project was conducted to evaluate the use of chlorine for the oxidative destruction of residual ammonia which may remain in ground water after in-situ uranium solution mining operations. The work tested the idea of the injection of high strength calcium hypochlorite solution into the mining zone to convert ammonia to nitrogen gas as a final clean-up process for ammonia removal from the ground water system. The paper details ammonia removal efficiency as a function of chlorine dose, reactant and product material balances, and how the concept may be used as a final ground water restoration process.

Jan 1, 1982

By G. A. Kordosky

The control of pH in solvent extraction circuits is an old technique (1,2) but one which has a large potential for future use. The equilibrium position of any reaction which has hydrogen or hydroxide ions, either as products or as reactants, can be controlled by pH adjustment. Several examples of reaction types which are important in solvent extraction systems and which also show a pH dependence are shown in Figure 1. The examples were chosen to show the wide variety of reactions which fit the above criteria, but it is not meant to be a complete listing of all the possible reaction types, Some of the reactions are presented in a simplified form. It is the intent of this paper to discuss pH controlled solvent extraction reactions for some relatively simple systems through more complex ones.

Jan 1, 1979

By S. Yap, F. J. Sotillo, L. P. Irwin, F. M. Utsey

Slimes, especially clays, are detrimental to several processes in the Mining Industry. The efficiency of classification, clarification, gravity separation, and flotation decreases significantly in the presence of slimes and clays. This problem is particularly critical in the Phosphate and Sulfide Industries. To reduce the effect of slimes in mineral processing, several desliming techniques and chemical additives are used, such as sodium silicate, sodium carbonate, sulfuric acid, tripolyphosphate, hexameta phosphate, etc. Lately, the Mining Chemical industry has shift to more “Specifically Developed” reagents that offer the most efficient and cost effective performance, mainly using organic polymers. For this purpose, the Mining Chemical Industry needs to understand the crystal chemistry of minerals, the chemistry of the aqueous media, the interactions in solids-aqueous-gas interfaces, the rheology of the system, and the plant operation conditions and parameters. This paper describes the use of surface chemistry fundamentals on the design of an organic polymer capable of modifying the rheology of clayish slurries of a phosphate ore. The change in the rheological characteristics of the clayish phosphate slurries allow fine ore particles to settle faster by reducing the slurry viscosity. Thus, abetter separation of the ore from the slimes is possible using gravitational or centrifugal forces. As examples of the application of this reagent, industrial and pilot plant tests on desliming using tanks and hydrocyclones are presented. These tests showed the reduction of 32%-36% in ore losses for different phosphate ores during desliming operations, and the increase of cyclones desliming efficiency to 80%. Tests were also carried out to improve the rejection of unwanted iron bearing slimes in phosphate feed. These tests demonstrated that it is possible to reduce by 0.25%-1.23% Fe2O3content in the flotation feed product. As a result, significant economical benefits are observed with the use of this new technology without any adverse effect on down stream operations, such as clay settling or phosphate flotation.

Jan 1, 2003

By J. A. M. Cano

With a view toward increasing its product competitiveness in the foreign market, SAMARCO MINERACAO S/A has developed high MgO type pellets at its pilot plant for performing direct reduction simulation tests. Additives such as dolomitic lime and magnesite were used for increasing pellet MgO content. Comparative direct reduction simulation tests were conducted both in SAMARCO and foreign laboratories. The test results showed that it is possible to produce direct reduction type pellets with satisfactory metallurgical properties, which can be successfully processed at increased temperatures in direct reduction furnaces.

Jan 1, 1992

By Nobuharu Isago, Atsushi Kusaka, Kosuke Kawata, Dohta Awaji

"The immediate ring closure method, in which the entire periphery of the excavation area is closed immediately with an initial support within a short distance from the excavation face, has been increasingly used in Japan, especially, as one of the most effective countermeasures against difficult ground conditions in conventional tunneling. For reasonable design of this method, the performance requirements for the initial support should be clearly stated. The analysis of construction data of 30 road tunnels and the three-dimensional numerical modeling based on real data suggest that the immediate ring closure stabilizes the tunnel structure and the ground around it because of the inner pressure effect of the initial support, especially, for low ground competence factor and small internal friction angle. Finally, the bending compressive strength and the cross-sectional geometry of the initial support have to be considered in the tunnel design while considering the earth pressure and ground properties. INTRODUCTION Conventional tunneling methods often deal with difficult ground conditions such as soft ground or squeezing ground conditions. The immediate ring closure method, in which the entire periphery of the excavation area is immediately supported within a short distance from the excavation face (Figure 1), has been increasingly used in Japan as one of the most effective countermeasures against difficult ground conditions in conventional tunneling (e.g. Takahashi et al., 2011; Nakaoka et al., 2013). The immediate ring closure method was empirically identified as effective for reducing ground surface subsidence and tunnel deformation. However, the working effects of the method have not been clarified sufficiently. To improve the design of this method, the working effects of this method and the performance requirements for the initial support need to be clarified. The relation between the effect of immediate ring closure and earth cover has been clarified (Mashimo et al., 2008; Awaji et al., 2013),"

Jan 1, 2016

By Kenneth G. Colman

Even though wet processes were used in coal preparation plants prior to 1941, dewatering coal was not a problem then because the finer sizes were uneconomical to recover and were considered waste. However, during the war years the scarcity of raw materials necessitated the utilization of every pound of natural resources and coal plants began seeking an economical mans of recovering fine coal. Early efforts to this end concentrated primarily on centrifugal dewatering devices. Such equipment produced good results but was relatively expensive. In 1944, a method was devised utilizing a vibrating screen fitted with a profile wire deck rather than the standard woven wire cloth deck. This machine came to be referred to as a dewaterizer. Results obtained with the dewaterizer approached those of the centrifugal equipment, but at a lower capital cost, Their use reduced either the number of centrifugal units required to follow the dewaterizers or the required energy input to heat dryers, In some cases they eliminated the need for any further dewatering equipment.

Jan 1, 1970

By Ronald C. Severson

Crystals of native gold occur in placer-type deposits. Gold, as a pure metal, is the most malleable metal known; therefore, delicate gold crystal forms should not survive mechanical transport and concentration processes involved in placer formation. To test the hypothesis that the crystalline gold is currently forming in place, two active gold-placer operations and an unmineralized background area in Alaska were examined. At these sites, rock outcrops, soil profiles, and native vegetation were sampled. At one sampling site, the soil was panned and yielded crystalline gold, as well as the more common rounded nuggets. The plants and soils were analyzed for their major, minor, and trace-element contents, especially gold. Two procedures, one a simple demineralized water leach and the other a partial digestion with acetic acid and hydrogen peroxide, were also used to extract gold and various anions from soils. The water-extractable gold ranged from <0.02 to 15.0 ppb Au in the extracting solution. This represents as much as a 104 enrichment in gold over average river water. This extractable gold is probably available to the native vegetation. Gold concentrations in the unashed dry plants from the two placer sites ranged between 0.4 and 106 ppb compared to a background range of <1 to <4 ppb Au. The presence of dissolved organic matter in the soils is thought to be responsible for the dissolution, transportation, and precipitation of gold in these placer soils, and this process is presently active in these soil profiles.

Jan 1, 2013

This paper reports on the behavior of mercury and its compounds during the thiosulfate leaching and recovery of gold. Thiosulfate solutions are shown to dissolve Hg0 and Hg2Cl2 to a similar extent as cyanide, but the leaching of HgS is significantly slower in thiosulfate solutions compared to cyanide. Hence, the use of thiosulfate may be an option for treating ores containing high levels of cinnabar, especially since the legislation concerning the discharge or sale of mercury is becoming more restrictive. The deportment of mercury during gold thiosulfate loading and recovery using a strongly basic anion-exchange resin was also studied. Although the mercury thiosulfate complex loads on the resin, the adsorption is weaker than for gold, with an equilibrium constant between gold and mercury of 51. Resin loaded with gold, mercury and copper was pre-eluted with thiosulfate (to remove copper) and eluted with a chloride and sulfite eluant. The majority of the mercury is eluted by the eluant and, hence, its deportment closely follows gold and the eluate would need to be treated to remove either mercury dur-ing or prior to gold electrowinning.

Jan 1, 2010

By M. Ge

An in-seam seismic (ISS) - based void detection technique was developed and tested for three general mine conditions: anthracite, bituminous and trona. The detection range tested varied from 80 to 100 m for trona mines and from 33 to 66 m for bituminous mines. High quality and broad band signals were obtained from these tests and were used to delineate the voids. The paper provides a brief discussion on the technical features of this void detection technique, the testing conditions and results, and a general assessment of the technique.

Jan 1, 2010

By Y. Guan

The dissolution behavior of silver and copper from silver/copper alloys in ammoniacal solutions has been investigated using a rotating disc. Oxygen was used as an oxidant. The effect of composition of alloys, concentration of lixiviants, stirring speed and temperature on the overall dissolution kinetics has been studied. Silver / copper alloys of three compositions were used in this study. The atomic percents of silver in these alloys were 76.9, 46.9 and 24.1. The results on the rate of dissolution obtained for these alloys have been compared with that of pure silver and copper under the same testing conditions. A particular emphasis has been given to the galvanic effect on the overall dissolution rates.

Jan 1, 1993

By G. H. Kuhnhausen

The Bear Creek Uranium Mill was designed in 1975 to process 909 tonnes per day (1000 STPD) of low-grade uranium ore from the Powder River Basin in Wyoming. The mill was expanded to 1818 tonnes per day (2000 STPD) in 1979. The Bear Creek Uranium Project is owned by the Bear Creek Uranium Company, a partnership of Rocky Mountain Energy Company and Mono Power Company. The original mill design contemplated processing ores from Bear Creek Uranium Company properties exclusively. The expanded capacity has been utilized for tolling ores from Kerr McGee Nuclear Corp. and other mining companies in the region. This paper describes the process of designing the original mill, the lessons learned from operation, and the design of the process modifications required for expansion. The project background, design philosophy, design basis, design criteria, actual flowsheet, special design considerations, and a comparison of assumed operating conditions and actual operating results will be presented. Bear Creek Uranium Company wishes to thank and acknowledge the help granted by the many operating companies who provided invaluable information, insight, and critique of the Bear Creek design through all the various stages and were instrumental in the successful completion and start-up of the mill. Without their contributions, the design philosophy used at Bear Creek would not have been possible and the results obtained would surely have been less satisfactory.

Jan 1, 1979

Thermal pretreatment can significantly improve industrial comminution operations by reducing energy requirements and increasing mineral liberation. The effect of pretreatment using conventional and dielectric heating followed by quenching on the fracture properties of a number single and multiphase brittle materials has been investigated. The reduction in the impact fracture energies and particle strengths with and without pretreatment has been measured in precise single-particle experiments using the Ultrafast Load Cell. Variations in the fragmentation pattern caused by different pretreatments were assessed by measurements of the progeny size distributions. The differences in the effect of thermal treatment on single and multiphase materials are discussed based on the experimental results.

Jan 1, 1995

By H. R. Manouchehri

The responses of calcite, feldspar, and quartz minerals In a laboratory free fall electrostatic separator, before and after tribocharging with stainless steel, PVC, and copper plates, have been investigated. The effect of H3BO3 and BaCl2 chemicals pre-treatment on the electrical properties of the minerals is examined. The changes in the electrical properties are discussed with the determined charge, dielectric constant, and electrical conductivity of the mineral samples. Electrical properties of the minerals and their responses to the electrical field during separation, after tribocharging and chemical pre-treatment, are explored for the need to characterize the electrical behaviour of the minerals.

Jan 1, 1998

By R. Cohen-Alloro

Classical apparatus for granulometric separation generally have limited applications which are found either in the level of the size of separation or in that of the accuracy and the efficiency of the separation or in that of the rate of feed. In industrial practice, the classification of the products of coarse dimensions generally poses no problems. On the contrary, the separation of fine particles presents some difficulties, however the apparatus is used (mechanical classifiers, curved screens and sieves, hydrocyclones, etc...). These difficulties are due to hprfections of separation, rather high cost prices, and sometimes large amounts of recycled materials.

Jan 1, 1970

By S. Zaharia

The authors present the state-of-the-art regarding natural and anthropic hazards on the stability of the saliferous Costiui basin. The factors that may potentially result in sliding, piping and collapse, are emphasized, given the existence of a large number of old salt mines. Also, a geotechnical risk map of this hydrosalt complex in Romania is presented.

Jan 1, 2008

By S. S. Klima, A. L. Mazzella, J. S. Driscoll, T. W. Beck

Previous testing was performed by researchers at the National Institute for Occupational Safety and Health (NIOSH) to improve longwall dust control using underside shield sprays with a longwall directional spray system. This testing provided encouraging results toward respirable dust exposure reductions for longwall personnel, achieving as high as 99% dust reduction at some sampling locations along the longwall personnel walkway. Additional laboratory testing was conducted to test these underside shield sprays in conjunction with a shearer-clearer spray system located on the longwall shearer body. The purpose of this testing was to determine if the underside shield sprays interacted positively or negatively with the shearerclearer sprays. Results from this testing indicate that while the shearerclearer system influences where the respirable dust particles are directed, underside shield sprays can still lower respirable dust exposure for longwall personnel.

Mar 2, 2022

By A. Haghighat, B. Lattimer

"Mine face ignition due to a high levels of methane is one of the most common fire incidents in underground coal mines. This work exams ignition scenarios in continuous miner headings. Depending on the magnitude of the ignition or resulting fire, the ventilation curtain in the continuous miner (CM) heading may be damaged or dislodged, affecting the ventilation into the area. A computational study was conducted to investigate the effects of different levels of damage to the ventilation curtain on the ventilation flow into the CM area. The computational fluid dynamics software Fire Dynamics Simulator (FDS), Version 6.0 was used to predict the conditions that develop due to a 200 kW fire in the coal mine face following a methane ignition with different levels of curtain damage. Smoke layer depth, temperatures and mass flow into the CM area were used to evaluate the impact of no damage to the curtain, partially dislodged curtain, and fully removed of the curtain. Partial removal of the curtain allowed more smoke to accumulate in the CM area and a reduction in ventilation into the CM area. With full removal of the curtain, the smoke accumulated through the entire depth of the CM area and flowed out the entrance to the CM area and the ventilation completely bypassed the region. INTRODUCTION Active working faces in underground coal mines are one the most hazardous locations in terms of fire events. According to Mine Safety and Health Administration (MSHA) data analysis, the highest number of non-fatal fire incidents was reported at mining faces, intersections and crosscut areas in comparison with other locations from 2000 to 2012. About 464 fires happened at active working faces from 2000 to 2012, most consisting of a methane ignition, in some cases followed by localized fire. These are high risk incidents due to the potential to raise float dust and damage ventilation systems, particularly auxiliary systems such as curtain or tubing. Depending on the magnitude of the ignition or fire, the ventilation curtain in the continuous miner (CM) area may be damaged or dislodged, affecting the ventilation into the area. Five computational fluid dynamics (CFD) scenarios were considered to investigate the smoke layer depth, temperature, visibility, mass flow rate, and the behavior of airflow in an entry with a continuous miner (CM) located in it. The state of the auxiliary ventilation was varied based on the assumption that as an ignition increases it magnitude it will affect ventilation curtain proportionally. Visibility and temperature along the height of the entry at different sections were investigated and the interface height at each section was determined. Also, the fresh air height was studied for tenability analysis in future. FDS, Version 6.0 was used to predict the conditions that develop due to a 200 kW fire on the coal mine face following a methane ignition with different levels of curtain damage. Smoke view software was used as the post processor to visualize and analyze methane fire behavior at the face. Most entry fires are reported as fuel-controlled fires as they are rarely restricted to air access (Ingason et al, 2014). The working face fire in the following models was assumed to be a fuel-controlled fire."

Jan 1, 2016

By V. Nasri, P. Jarast, M. Bakhshi

The Montreal metro Blue Line Extension toward the northeast consists of the construction of five new underground stations. The project includes 6 kilometers of the tunnel which will be constructed using a Tunnel Boring Machine (TBM). In line with the commitment to integrating sustainability best practices, Envision verification is pursued this project. The Envision reference framework was developed to cover all the sustainable development aspects of an infrastructure project and each phase of its life cycle (planning, design, construction, operations and maintenance, and end-of-life). As a part of this endeavor, low-carbon concrete and shotcrete mixtures are proposed for the linings of TBM and SEM tunnels as well as stations and auxiliary structures. The CO2 emission of the low-carbon concrete and shotcrete mixtures were compared with their typical mixtures and the total CO2 emissions reduction related to the tunnel lining is determined. The study is of strategic significance for achieving emission reduction in the tunnel industry.

Jun 13, 2023