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By James R. Boyle

The value of Alabama's nonfuel mineral production in 1984 was $409.8 million, and established a new record high for value of nonfuel minerals in the State, at 13.4:% over the previous high of 1983. Output of nearly all nonfuel minerals increased; phosphate rock was one of the exceptions, with no recorded output in 1984. Cement, crushed stone, lime, sand and gravel, and clays were the major commodities produced in Alabama. Alabama led the Nation in the production of crushed marble; was second in bauxite; third in fire clay and kaolin; fourth in bentonite, ferroalloys, and dimension marble; fifth in masonry cement, lime, and recovered sulfur; and sixth in portland cement. Alabama ranked 22d in the Nation in value of nonfuel minerals produced.

Jan 1, 1986

By E. Chin

Under the seventh 5-year plan (1986-90), the Chinese Government continued to implement reform and to open the country further to the outside world in order to accelerate the growth of its national economy. As a result of expanded foreign economic exchanges and domestic achievements in education, science and technology, and cultural and public health undertakings, the national economy was strengthened. In 1988, there was impressive growth in the Chinese economy. The gross national product (GNP) grew by 11.2070 reaching $373.4 billion; 2 the national income grew by 11.4070 to $310.9 billion. The major problem in the Chinese economy was the imbalance between high demand and insufficient supply. Chronic shortages resulted in price increases and high inflation, which averaged 19% for China as a whole and about 30% in urban areas. Macroeconomic stability took precedence over market-oriented reform initiative. Because of rapidly growing inflation, the Government re-imposed price controls and rationing in major cities in the fall of 1988. China continued to be a major world producer of minerals, metals, and fuels. Output of the principal commodities continued to rise. The largest in-crease in production was salt which rose 24% in output in 1988; followed by sulfuric acid, 14%; cement, 12%; soda ash, 9%; caustic soda, 7%; and steel, 6%. For fossil fuels, the increase in output of natural gas was 14% in 1988; followed by coal, 3%; and crude oil, 2%. The output of electricity by thermal-fired powerplants rose by 9% while that for hydroelectric power-plants rose 7%. Although China's overall energy output has increased annually since 1980, the growth in demand continued to outstrip the supply.

Jan 1, 1990

By W. J. Miles

At the beginning of the 20th century, barite was a mineral of minor importance in the USA. Its primary use was to extend lead oxide in white paint. Barite also added the special qualities of hiding power and flatness to paint. Because white lead sometimes turns black or yellow and barite does not, ground barite became a pigment on its own merit. Barium chloride was added to bricks before firing to stop efflorescence when exposed to weather. Barium carbonate or nitrate added luster and brilliance to glass. Barium chemicals were added to refining sugar, enameling iron, making oilcloths and paper collars, and in the manufacture of paper, artificial ivory, rubber and lithopone. Lithopone became a major paint ingredient in the 1920s; its use lasted until the 1950s, peaking at 150,000 metric tons of barite in both 1937 and 1947 for the manufacture of lithopone. Later in the 20th century, titanium dioxide replaced lead oxide, barite and zinc oxide in the coatings industry. In the 21st century, barite is used as a filler, extender, or weighting agent in products such as paints, plastics, and rubber. Some specific uses include its use in brake and clutch pads for automobiles, automobile paint primer for metal protection and gloss, add weight to rubber mud flaps on trucks, and add weight to the cement jacket around petroleum pipelines under water. In the metals casting industry, barite is part of mold release compounds. Because barite significantly blocks X-ray and gamma ray emissions, it is used as aggregate in high density concrete for radiation shielding around x-ray units in hospitals, nuclear power plants, and university nuclear research facilities. Ultra-pure barite consumed as liquid is used as a contrast medium in medical X-ray examinations. Barite is the raw material for barium chemicals, such as barium carbonate, which is an ingredient in faceplate glass in the cathode-ray tubes of televisions and computer monitors. In the 21st century, barite industrial uses account for an estimated 78,000 tons per year in the United States. Another barite use was patented in 1926 by the oil industry. In this patent, barite is primarily used as a non-abrasive weighting agent for drilling for oil and gas exploration and production. As a weighting agent, it provides the downward force in a water based or oil based drilling fluid for cutting through rock with a tri-cone diamond drill bit. In order to minimize the wear on the drill bit and drill stem, minimum abrasion of the weighting agent is preferred. In recent years in the USA, 95% of the barite produced and about 80% on a world basis are used as a fluid weighting material during the search for oil and gas. During the latter part of the 20th century, barite was used in the drilling mud of oil and gas wells, particularly for wells deeper than 2000 meters, and petroleum well drilling demand for barite became the mineral?s major end use during economic expansions after World War II and subsequent increased use of oil and gas in the USA. The profitability of oil and gas production had a strong effect on the number of drill rigs and consumption of barite. The United States was the leading petroleum well drilling country starting in 1970, reaching 4,530 drill rigs in December 1981, and was the largest consumer of barite. In the USA, record highs of about 2.6 million tons of barite produced and 4.3 million tons consumed were reported in 1981. From 1997 to 2006, barite production declined from 662,000 to 589,000 metric tons. However, USA imports increased from 1,470,000 to 2,530,000 metric tons for lump barite. World production of barite increased from 6,780,000 to 7,960,000 metric tons during the same period. Table 1 (see Appendix) lists USA production, imports and exports and world production from 1997 to 2006. Major sources of imported barite include China, India and Morocco. Table 2 (see Appendix) lists the USA imports and price of barite by country. China, India and Morocco are the three largest exporters of barite to the USA and the world. Vietnam is a new producer, beginning in 2006. IMPACT OF CHINA ON DRILLING GRADE BARITE In the 1970s or before, China began supplying barite to the world drilling market in order to help develop their economy. When China first entered the barite export market, their high production volume, low pricing and low ocean transport expenses to the Gulf Coast forced barite producers in the USA to supply only regional markets, such as Battle Mountain Nevada barite for the western and Rocky Mountain states and Canada. Until recently, it was China?s government policy for domestic consumers to use barite below the API 4.20 specific gravity specification, leaving higher grades for export, but this is no longer the case. In recent years the internal demand for barite in China increased tremendously as their economy rapidly developed. China reduced their former 15% VAT tax rebates to 5% for Chinese barite producers, and then eliminated all VAT tax rebates on December 15, 2006. On the supply side, some high-grade barite deposits in China have been depleted. In particular, the low heavy metals sources are less plentiful. Additional mine capacity is being developed, but the new mines are underground and therefore costs will be higher. China?s appetite for other raw materials has tied up a large portion of the world?s bulk vessel fleet, including Panamax vessels (preferred for barite ore transport). Ocean transport freight rates have increased in recent years, and receiving ports in the USA are congested with imports of higher-added-value products. The Panamax Index, which tracks maritime shipping rates, more than doubled in 2006. China has also devalued its currency from RMB8.30 to RMB7.80 per dollar. These factors are driving up the import price of crude and ground barite for drilling. In addition, in the USA, rail congestion and high fuel prices led to higher trucking rates, increasing the delivered cost of ground barite to oil customers. India is the second largest supplier of crude barite to the USA and world drilling market. It produces all of its barite from a single deposit in the Cuddapah region of Andhra Pradesh State. More than 90% of production comes from the State-owned Andhra Pradesh Mineral Development Corp., and the government continues to closely control production, export volumes, and prices. India saw a dramatic increase in barite prices as a result of its last 3-year tender in 2004. However, in 2004 and 2005 their shipments of crude barite to the USA were not significant. In 2005, India began supplying barite pulverized to meet API specifications to the Gulf Coast. In 2006, Indian production was reduced owing to severe flooding in November 2005 that curtailed mining until mid-April 2006. Morocco has been the third largest supplier of crude barite to the USA and world drilling market. In 2003 and 2004 their shipments of crude barite to the USA were not significant. In 2005, Morocco resumed shipment of crude barite to the Gulf Coast and began supplying barite ground to meet API specifications to the Gulf Coast.

Jan 1, 2009

By Christian Heili

In 1991 the Government of the Republic of Zambia passed legislation providing for the privatisation of Zambia Consolidated Copper Mines Limited (ZCCM). The newly formed Mining Companies, established after nearly a decade of difficult and protracted negotiations on such matters as, cash at close; retained percentage interest by ZCCM; equity investment; future investment commitment and tax concessions, were faced with great internal challenges and a harsh external environment. There was a convergence of a number of negative forces that had and will continue to have an impact on the mining environment in Zambia. The most crucial of these being, the competitive pressures of the global economy, fluctuating copper price and the prevailing HIV/AIDS pandemic. In the short period after privatisation, the Industry has seen the collapse of Binani Industries (Luanshya Mine), the withdrawal of Anglo America Corporation from Konkola Copper Mines Plc and the disposal of Chambishi Cobalt and Acid Plants by Anglovaal Mining Ltd. The objective of this paper is to provide a theoretical and practically researched foundation, which may be used to assist Zambian Mining Companies in making informed decisions on the issue of Strategic Outsourcing and the degree to which this may support the successful and sustainable growth of the Zambian Copper Mining Industry. If judiciously implemented, Strategic Outsourcing has the potential to generate a practical business valuation and process to assist Mine Management in the achievement of their business goals and consequently the return on investment to their Shareholders.

Jan 1, 2005

By Lee Browne

The transformation of Peru’s Tintaya copper project from a state-owned company to a private company is under way and the results have been successful. Since Magma Copper Co. assumed operating management in December 1994, production and costs have improved dramatically. To understand the transformation of Tintaya, the transformation of Magma Copper must also be understood.

Jan 1, 1996

Ohio has an estimated 46 billion tons of coal beneath 12,000 square miles of the eastern third of the state. Recoverable coal reserves within this vast area are estimated at 21 billion tons, 3.2 billion tons of which have been mined since 1800. Ohio is the eleventh-largest coal- producing state in the nation and ranks third nationally in coal consumption. Coal resources in Ohio lie in as many as 60 identifiable coal seams along the northwestern flank of the Appalachian coal basin. Except where interrupted by minor faults and erosional discontinuities, these rocks dip gently and uniformly to the east, simplifying the mining methods needed to extract the coal. Fourteen of Ohio's 60 coal seams are considered to be important, although only a small number of seams are currently being mined. Ohio first enacted a surface coal mining law in 1948, requiring in part a $100 per acre reclamation bond. Ohio progressively strengthened its surface mining law in 1949, 1955, 1959, 1961, 1965,1972,1975,1978, and 1981. At the time of its enactment, Ohio's 1972 mining law was one of the most stringent in the country. This law also created a state coal severance tax of four cents per ton to be used for abandoned mine land reclamation. Ohio received primacy to regulate the surface coal mining operations within the state August 16,1982. Its Abandoned Mine Land Program was approved on the same date.

Jan 1, 1992

By Scott Hopkins

Simulation tools are preferred for evaluating complex systems due to its ability to mimic reality and quickly evaluate many different what-if scenarios and find global solutions. A simulation model is capable of representing variable and dynamic disturbances that are typically encountered in day-to-day operations; this is where spreadsheet models or linear programs fall short because they cannot account for the dynamic behavior and relationships. The simulation model used for this work was developed by Xstrata-Nickel (previously Falconbridge). The simulation tool is very flexible and can be used to simulate different mining and development methods. The scope of the modeling included production mining, geology, equipment fleets, equipment maintenance and random failures, manpower, shift schedules, and cycle activity times. A case overview of the 170 Orebody will be presented along with the challenges associated with data collection for the model inputs. Results and lessons learned will also be discussed.

May 1, 2008

By Jean J. Abiassi

The Boston Marine Industrial Park (BMIP) VENT 6 project is a cut and cover tunnel, part of the Central Artery / Tunnel (CA/T) in the city of Boston. The BMIP job will serve as the south approach to the Third Harbor Tunnel crossing. The alignment is approximately 2500 Ft long and is made up of four sections starting from west to east: 1. West Tunnel 2. Boat Section 3. East Tunnel 4. Tunnel inside Vent 6 Cofferdam and connection to the Third Harbor Tunnel. The support of excavation (SOE) system for the West Tunnel, Boat Section, and East Tunnel are all a part of this project whereas the SOE for Tunnel inside the Vent 6 Cofferdam was a part of the contract for the Third Harbor Tunnel.

Jan 1, 1994

By Bart Bartholomew, Randall J. Essex

INTRODUCTION In June of 2004, at the North American Tunneling Conference in Atlanta, an all-day workshop was conducted to review the application of Geotechnical Baseline Reports (GBRs) for underground construction. The moderator for the program was Bart Bartholomew, former President of Fruin Colnon Construction Company. The program involved commentary by a panel of engineers, owners, contractors, and legal representatives within the North American tunneling industry, as well as an extended audience discussion. The panelists were: Peter Douglass, President, Peter Douglass, Inc. Randall Essex, Executive Vice President, Hatch Mott MacDonald Joseph Gildner, Deputy Director for Technical Services, Sound Transit Randall Hafer, Esq., Kilpatrick Stockton Robert Fitzgerald Esq., Watt, Tieder, Hoffer, & Fitzgerald Kirk Samuelson, Senior Vice President, Kiewit Construction Group DEVELOPMENT OF PROGRAM FORMAT The focus of the program was to assess the state of the practice in the preparation of GBRs, and to discuss improvements that could and should be made with regard to their preparation, interpretation, and application. The approach used to achieve this focus in the broadest possible way was unique, in that it involved the panelists’ preparation of the workshop format and materials months before the presentation of the workshop. First, each of the six panelists was selected by the moderator based on their reputation and involvement in their respective fields of expertise, taking care to maintain balance and contrast within the collective pool of talent assembled. Following selection and agreement to serve on the panel, each panelist was asked to independently submit to the moderator a list of the six most pressing issues involving GBRs that they each frequently encountered in their individual professional experience. Each was asked to rank their issues in descending order of perceived importance. This process resulting in a pool of thirty-six potential or “candidate” issues for use in the workshop program. Contrary to the moderator’s expectations, there was surprisingly little duplication among the thirty-six issues submitted.

Jan 1, 2005

By M. Botz

For leach solutions containing primarily free cyanide, the silver nitrate titration method is a rapid and acceptably accurate means of analyzing for cyanide. However, in leach solutions containing elevated levels of copper, the titrimetric method significantly over-estimates the concentration of free cyanide and under-estimates the concentration of weak and dissociable (WAD) cyanide. The authors have developed a modified potentiometric titration method for determining WAD cyanide that overcomes issues with high copper levels in solution. The new MP-WAD method involves addition of a chemical ligand to the sample prior to silver nitrate titration to fully release cyanide bound to copper. Once released from copper, cyanide in solution is no longer affected by the presence of copper and titration results are quantitative rather than empirical. In multiple laboratory trials with synthetic solutions and complex actual leach solutions, accurate WAD cyanide measurements were achieved using the MP-WAD method. Analyses obtained with the new method were found to be within about ±10% of analyses obtained with the USEPA OIA-1677 WAD cyanide analytical method.

Feb 27, 2013

By Earl L. Rau

At the present time, whether an electric utility uses high-sulfur coal is largely determined by geographical location, clean air legislation, and the age of the power plant. Acid rain legislation may well be the new force to change the use of high-sulfur coal. A number of coal papers were presented at the SME Fall Meeting in St. Louis, MO, Sept. 1986. These papers discussed high-sulfur coal in relation to its economics, trends and prospects, value of cleaned coal, and coal-cleaning technology. The Clean Air Act of 1970 required the reduction of SO, emissions from most stationary electric-generating plant to 0.5 kg (1.2 lbs) SO2, per million Btu of heat input. It was possible for many plants to utilize lower-sulfur coal or a mixture of high-sulfur and low-sulfur coal to meet this emission requirement. This 1970 act greatly increased the use of low-sulfur western coal. The 1978 amendment to the Clean Air Act required all new plants to use Flue Gas Desulfurization (FGD) to meet a requirement of 70% reduction of potential SO2 emissions to 0.3 kg (0.6 lb) SO2 per million Btu of heat input. With the requirement to use FGD, there was little or no demand for low-sulfur western coal in new eastern power plants. If' new acid rain legislation is enacted, it likely will require sizeable reductions in SO2, emissions by existing coal users. There might then be a shift to greater use of low-sulfur coals. The low-sulfur coals could come from either western or eastern mines or from cleaned eastern coals. Economics will dictate the approach older power plants will take to meet new regulationsuse FGD or low-sulfur coal. Coal use for electric power generation has changed from 1970 to 1985. Table 1, (Land, preprint 86-333) shows the change. The table shows that in 1985, US utilities used about 255 Mt (280 million st) of high-sulfur coal. Some 45 to 54 Mt (50 to 60 million st) of high-sulfur coal is being used in plants equipped with FGD and most of this use is in eastern states. This leaves 200 to 209 Mt/a (220 to 230 million st) of high-sulfur coal being used without FGD treatment. These plants are at risk if acid rain legislation is passed. Most of these plants are in the east and are more difficult to supply with low-sulfur coal. Estimates range from $20 to $30 billion capital investment and from $5 to $9 billion dollars per year operating costs to reduce SO2, emissions from those old medium-to-high-sulfur coal-burning plants. G. W. Land, (preprint 86-333), also presents tables relating to power generating costs and coal types. The author's tables are extracted from Land's tables IV and V. Table 2 here presents costs for a new plant. This includes the impact of different heat rates, fuel costs, fuel qualities, operating and maintenance costs, labor costs, and waste disposal costs. Table 3 compares estimated costs to retrofit an older plant with a limestone scrubber versus switching the same plant to low-sulfur eastern or western coal. Costs of switching include upgrading the electrostatic precipitator and - with western coal - costs of derating. Bhagwat, (preprint 86-325), details the trends in high-sulfur coal markets from 1974 to 1984. He also gives some prospects for high-sulfur coal markets, 1984 to 1994. The prospect depends mostly on whether acid rain legislation is enacted. By 1994, if New Source Performance Standards (NSPS) continue to be applied, high-sulfur coal demand from six mid-west and eastern states is expected to increase by 27 Mt (30 million st). • L. A. Khan and J. W. Baxter, (preprint 86-373), discuss several coal cleaning technologies such as froth flotation of fines, bulk oil separation and oil agglomeration, oil agglomeration/flotation, and air-floc flotation. ? (Space limitations preclude listing references. A complete list is available from the author.)

Jan 1, 1987

By R. W. Schutz

"Titanium possesses an exceptional and wide-range resistance to chlorides and their compounds when compared to most corrosion-resistant engineering alloys (CRAs) used in the chemical process industry. This natural resistance to chlorides stems from titanium’s protective, tenacious, and readily rehealable titanium oxide surface film, which is chemically stable over a wide range of pH and redox potentials in aqueous environments. This passive film explains titanium’s elevated resistance to anodic pitting, crevice and stress corrosion, and erosion-corrosion in aqueous chloride environments.Guidelines for successful selection and application of industrial titanium alloys are derived from an extensive laboratory test database and more than forty years of industrial/chemical service experience. These guidelines are simplified, and alloy corrosion performance is assessed with respect to four basic aqueous chloride service categories where selection or consideration of titanium is highly merited. An overview of historical titanium alloy applications in chloride-rich environments in a wide variety of process industries substantiates their exceptional chloride tolerance. These industrial titanium alloys are cost-competitive with stainless steels and nickel alloys, readily commercially available, and routinely fabricated and welded in the shop and field via well-established methods."

Jan 1, 2002

By R. D. Lawrence

Suggestions have been made that the appraisal of mining assets using discounted cash flow techniques should be based solely on proven and probable reserves in reliance upon the widespread international recognition of uniform resource definitions. Following a review of general accepted valuation principles, a survey of the literature and, most importantly, a review of real transactions in the open market, it is clear that valuators should not be constrained by the growing acceptance of modern mineral resource codes. On the contrary, valuation practitioners should be encouraged to examine all classes of mineralization and, after making due allowance for risk, to utilize all mineral resources as a basis for determining fair market value.

Jan 1, 2000

By J. A. Pile, Virgil Miller, R. G. Peterson, F. B. Petermann

"INTRODUCTION As virtually no published data are available on the sintering of fine, minus-100-mesh, ferrograde manganese ores, it is most opportune to present data on the amenability of various fine ores and mill products to the sintering process. These data cover the sintering or nodulizing of finely crushed, high-grade pyrolusite and rhodochrosite ores, sintering of manganese carbonate flotation concentrate, sintering or nodulizing the calcine from the deleading of a manganese oxide flotation concentrate, and sintering the calcines made in a Herreshoff furnace from the treatment of manganese sulfate products.If finely sized products are to be smelted in the present electric or blast ferromanganese furnaces, they must be sintered or nodulized. The only specification as to the size of the sintered or nodulized product is that it must pass a 6-inch screen and not contain over 1t-1/2 percent minus 20-mesh material. The minimum-maximum size has not been established. Undoubtedly this opti mum size will be set by the ferromanganese industry when ample quantities of manganese oxide sinters have been smelted."

Mar 1, 1942

By Jack A. McQuiston, Thomas A. Cross

Corrosion of equipment and machinery in the coal industry is usually the result of three main agents: acids, chlorides, and abrasion. Acids and chlorides are especially troublesome in coal preparation plants where soluble salts and sulfur in the coal produce a highly corrosive wash solution. Abrasion is common in all operations where coal is handled or conveyed. Together, the acid-chloride-abrasion combination results in some of the worst corrosive conditions found in any industry. The variety of equipment and structures in the coal industry calls for different corrosion control techniques. Table 1 lists the areas of concern for a number of items. Just as there is a wide variety of corrosion problems, there is a wide array of coating materials available. Tables 2 and 3 are selection charts to provide guidance in narrowing down the choices. Experience has shown that a limited number of coating systems work best on coal equipment and structures. These systems are described in Table 4. The good-better-best designation in the table refers to coating system longevity. Good indicates the least costly and shortest service life. In nearly all cases the lowest annualized cost can be achieved by using the coating system rated best, due to the avoidance of costly repaints and unnecessary downtime. The most expensive coating system, though, is worthless unless the coating system is properly applied. Field inspection to insure compliance with specifications is an important aspect, and is a service available from many coating suppliers. Even the best coating systems require periodic maintenance to achieve satisfactory results. Spot rusting from mechanical damage should be repaired annually to maximize the coatingsystem's results.

Jan 2, 1980

By Pedro Vargas Gálvez

El presente texto señala la metodología de selección del software de mantenimiento respecto a este mismo y a la Planta. Para ello, se detalla las condiciones que deberán considerarse en la Organización de Mantenimiento y la aplicación del Software de Mantenimiento MP2 a una empresa. Asimismo, se presenta el Plan de Implantación, los inconvenientes que se han encontrado así como los resultados obtenidos por la utilización del Software MP2.

May 25, 1998

By C. A. F. Sweet

The inter-relationship between these parties and the effect on the outcome of the project is often grossly underestimated. There are numerous success stories where the parties have worked as complementary teams aiming at the best outcome for the client company and achieving significant success. While there are a good number of occurrences where either the roles of the parties were unclear or perceived to be different from what others in the team believed or required them to be and the results were less than desired. This usually resulted in ongoing conflict, incorrect focus, working to different agendas and the result being a less than optimum result to Client Company. Mining, by its very nature of exploring where you cannot see, be it a shaft being sunk, tunnel being developed or other excavation that needs to be made, requires a very special working relationship between the parties. To understand this, and it applies equally well to mine and plant construction and other multiple function projects, one needs to start by describing the relationship of the parties. Often people believe that because they manage ongoing complex operations and large numbers of people that they can manage projects and as such the participants will ?fall into line.? At the outset it needs to be stressed that ?Project Management? is a specific type of management and needs to be understood as such. There are enough Colleges and Universities that teach project management, not only as a subject but also as a Master Degree. As you start up your project the relationship you establish between the client, project team (C.P.T) and the Engineering, Procurement, Construction and Management team (EPCM) will largely determine how successful your project will be. It is essential that from the outset a spirit of co-operation, support and respect be nurtured, and that it be actively carried through the project life cycle. There are several methods to facilitate this including team building exercises right at the start. This time and money will be well spent and recouped many times over during the project life cycle.

Jan 1, 2005

By Murray Gamble

A new type of groundwater cutoff wall has been developed at the University of Waterloo. The Waterloo Barrier? is a steel sheet piling system that incorporates a sealable cavity at each interlocking joint. In order to prevent leakage through the joints, the sealable cavity is flushed clean and injected with sealant after the installation of the piling. The installation and sealing procedures of the Waterloo Barrier? system allow for a high degree of quality control resulting in a very low permeability cutoff wall. Based upon field installations, the bulk wall hydraulic conductivity of the Waterloo Barrier? ranges from 10-8 to 10-10 cm/sec. Recent case histories are presented in which Waterloo Barrier? vertical cutoff walls have been used to prevent the off-site migration of contaminated groundwater or soil gases. In some instances, the Waterloo Barrier? system was used in combinations of applications such as preventing the migration of contaminants, redirecting the flow of groundwater, providing structural shoring for soil excavation and aiding in site de-watering processes.

Jan 1, 1997

By O. F. Brown

The use of quality materials (aggregates and asphalt binder) in optimal proportions is the key to producing optimally performing hot mix asphalt (HMA). The Superpave mix design standard in the US introduced specific volumetric and binder property requirements in HMA design. Different methods for HMA constituent proportioning have been proposed in various guidelines. The design process to determine the HMA blend is currently iterative and engineers rely almost exclusively on experience. This approach is time consuming and often does not result in cost-optimal HMA mixtures. This paper introduces a mixed integer linear programming (MILP) optimization model for hot-mix asphalt constituent proportioning. The MILP model minimizes the total mix cost while satisfying all the volumetric, binder and mix property specification requirements. The model has been successfully validated with real-life example. The aggregates and binder ratios from the model were in close agreement with those from the contractor. The Bailey ratios and the gradation constraints were also satisfied. The cost of the optimal mix was $0.804/Mg less than that of the contractors?. This marginal reduction might make all the difference in an industry that is highly competitive. The MILP model also demonstrated that adding RAP to the contractor?s design would reduce the cost of the blend by $5.74/Mg. The virgin binder content was reduced by 1% because of the recycled asphalt contained in the RAP. This work represents the first successful attempt in incorporating both aggregate and asphalt performance requirements into the optimization formulation. Applying these models will ensure the minimum cost mix that meets all constraints and will increase profit margins for plant operators.

Jan 1, 2012

By Steve Dillingham

Whenever misfired holes or portions of misfired holes remain after a blast is fired, a hazardous situation exists until the unfired explosive materials have been disposed of properly. Yet, there are so many factors that can contribute to misfires that it is impossible to give blanket instructions on how to handle them. To complicate matters, misfires today are rare due to reliable blasting products. As such, it isn’t very surprising that many blasters have never had to deal with a misf i re condition. While the likelihood of a misfire occurrence is minimal, you should always be pre p a red to handle a misfire should you be involved in such an event. To begin, every blaster and blasting org a n i z a t i o n should develop a misfire policy which contains the company’s safe operating pro c e d u res, emergency contact list, as well as any regulatory compliance re q u i re m e n t s . Tailgate and/or company-wide safety meetings should communicate the company’s contingent misfire pro c ed u res and any special site-specific precautions BEFORE the start of any project.

Jan 1, 2004