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By Dejan Petrović, Pavle Stojković, Jelena Ivaz, Saša Stojadinović

In spite of the fact that flyrock phenomenon represents the real threat for personnel and machinery, it still remains insufficiently investigated. There are efforts, in the mining community, to explain the causes of flyrock, but the models capable to accurately predict flyrock occurrence and define the flyrock distance still do not exist. This article is an attempt to establish such a predictive model. The model utilized the adaptive nature of artificial neural networks and combined it with the accuracy of numerical modeling of physical phenomena. Necessary data were collected by high-speed camera recordings of actual blasts at three different surface mines and processed for further use for artificial network training. The result was a neuro-numerical couple which was capable to predict flyrock occurrence, estimate the launch velocity of flyrock fragments, and calculate the maximum distance of flyrock fragments. The safe distance was then calculated by multiplying the flyrock distance with a factor of safety. The article explains the procedure for data acquisition and processing, artificial network construction, training, and validation. It also explains the principles of flyrock distance calculation and, finally, provides a definition of factor of safety and safe distance. The results showed that the prediction was satisfactorily accurate and reliable.

Oct 22, 2021

North American Coal is a subsidiary of NACCO Industries. Originally founded as Cleveland and Western Coal in 1913, North American Coal took its present name in1925. Today, North American Coal is one of the 10largest coal producers in America, mining about 32Mt/a (35 million stpy). The company mines primarily lignite for electric utilities. Its current operations are in North Dakota, Texas, Louisiana, and Mississippi. In addition, North American Coal’s Florida operation provides dragline mining services for quarries that produce more than 18Mt/a (20 million stpy) of limerock. With more than 1.8 Gt (2 billion st)of bituminous and lignite coal re-serves in the United States, North American Coal constantly seeks new technologies to keep its operations modern, productive and cost competitive.

Jan 1, 2004

By Paul A. Roy

The North Shore Connector Project for the Port Authority of Allegheny County constructs twin Tunnel Boring Machine (TBM) tunnels through cohesive soils and rock beneath the Allegheny River and a narrow city street in Pittsburgh, PA. The tunnel alignment includes an historic building on shallow foundations, modern buildings on deep foundations, and an office building constructed directly over the alignment during the design of the tunnel sections. This paper provides an overview and update of the general site conditions, TBM tunnel design, and support of excavation for the TBM launching pit. Deformation limits, ground improvement, monitoring and mitigation plans are also discussed.

Jan 1, 2008

By M. M. Rajkovich, L. Adams, J. J. Zaluski, S. Gardner

In 1998, Kentuckians for the Commonwealth filed an Administrative Petition with the Kentucky Natural Resources and Environmental Protection Cabinet to designate 8,903 +/- hectares (22,000 +/- acres) on Black Mountain, which contains the state’s highest point, as unsuitable for mining. A fast track legislative process was triggered which could have "taken"100 million tons of coal reserves or, in the alternative, imposed severe restrictions on mining. Even with all parties represented by reasonable individuals, this process can be extremely cumbersome and expensive. The legal and technical preparation for this unusual hearing process as well as issues and strategies of the negotiated resolution are reviewed.

Jan 1, 2000

By Paul Bartos

Operations at the Sweet Home Mine transformed the mineral specimen industry, not only in the development of new innovative extraction techniques, but also in the fields of sample preparation and marketing. Principally as a result of the activities at the Sweet Home Mine, there is now a better appreciation of minerals and the market they encompass. Individual Sweet Home rhodochrosite specimens have been sold for more than $1 million, with many more in the five- and six-figure dollar range. This article is a review of the Sweet Home operation, with emphasis on its extraction techniques. District history The Sweet Home Mine is located within the Alma mining district in the Mosquito Range of central Colorado, approximately 6 km (3.7 mile) northwest of the town of Alma at the base of the Red Amphitheatre in Buckskin Gulch at an elevation of 3,440 m (11,286 ft). Other nearby mining districts include Climax, Leadville, Breckenridge and London. All are considered part of central portion of the Colorado Mineral Belt (Fig. 1).

Jan 1, 2007

By Francesco Chiappalone, Filippo Azzarà, Raffaele Aliberti, Daniele Nebbia, Lance Waddell

As part of the 3RPORT and NEBT Projects, 5-mile Combined Sewer Overflow Tunnels were excavated with a 19 ft diameter Slurry and 26 ft diameter EPB Tunnel Boring Machines. Due to the difficult geological and hydrogeological conditions, both tunnels were excavated maintaining a ground support pressure between 2 and 5.5 bar imposing significant challenges to the projects. The first part of the paper describes the general characteristics of both projects while the second part focuses on the challenges and technical details of the pressurized breakthroughs that took place in deep shafts excavated in urban environment as part of the projects.

Dec 1, 2022

By J. Gholamnejad

In open pit mine planning and design, push back mine sequencing is widely used for long-term production planning. In push back design, a series of nested pits is generated and then considered as possible push backs with regard to the minimum push back width requirements. These nested pits are produced by parameterizing on one economic parameters like commodity price, mining or processing cost, stripping ratio etc. The most important characterization of these push backs is that the inner most push back has the highest value per ton, the second inner most push back has the second highest value per ton and so on. These nested pits are generated based on the best estimates of grade within a representation of the ore body in a three dimensional matrix form. Therefore, the inherent uncertainty associated with reserve estimation (for our discussion grade uncertainty) is not taken into account when push backs are designed. These methods do not attempt to establish which part of the deposit is likely to be worth most. This paper introduced a new algorithm that incorporates ore grade uncertainty during push back design process. The suggested strategy tries to seek to schedule risky blocks later in the extraction sequence.

Jan 1, 2007

By Thom Seal, S. J. Jung

This paper will combine three SME annual meeting presentations on reducing gold inventory in cyanide heap leaching. Information on Part I – Side slope leaching (SME 2003), Part II – Determining the dry zones using geophysical resistivity (SME 2004), and Part III - Presents a new technology “Hydro-Jex”, to introduce the required lixiviants to the un-leach or under-leach zones in heaps (SME 2005). This paper will describe how Newmont Mining Corporation continues to improve the economics of the heap leaching process for precious metals recovery.

Jan 1, 2005

By M. Javier

Mining, waste is growing problem both physical accumulation and increasing toxic uncertainties it presents in the long run. Its value ?zero? is strictly calculated by economy. This mining model begs the question: What is the value of waste & what does it represent to the mining industry? Waste is widely accepted as a ?by product? generated as a consequences of the mining process. The abundant waste accumulation affects society, as receptor, in many ways and the waste piles of materials has no use and no destiny. In reality, this waste is monument of imperfection of the extractive industries worldwide. Our planet is finite and has strict limitations, which mining has traditionally ignored. It is time to design a new system, in which clearly, waste design must be integrated in whole mining process; it has no room to postpone. This paper presents a concept in waste design by which toxic mining waste not only can be rendered inert but also act as nutrient to help balance the ecosystems. This concept calls for extractive industries to pursue EQUILIBRIUM with nature (Geomimic). Also, this concept offers countless gains and opportunities fro the industry and by converting liabilities into assets; mining engineers become the managers and stewards of nature. Also, waste design offers new solutions for proper and sustainable waste management of the mining industry.

Jan 1, 2011

Bortech’s BoreClad corrosion protection system will be displayed at MINExpo. BoreClad is an innovative system for inside diameter cladding of nozzles, tubes and other circumferential devices. Pressure vessels, mud pumps and other mining equipment must be protected from corrosive caustic chemicals. Usually manufactured from mild steel, they can be clad with a protective material, such as stainless steel, to provide corrosion resistance. However, most welding processes leave voids where corrosion can damage the base metal. BoreClad provides void-free welds by combining gas metal arc welding with automated feed and rotation of chuckable parts. Workpieces of up to 915-mm- (36-in.-) long with a 460-mm- (18-in.-)swing can be clad with stainless steel, Iconel or other exotic metals. In addition to eliminating the voids associated with hand welds, BoreCladcan lay more than 2.2 kg/h (5 lbs/hour) of metal. That is a significant reduction in weld time. Web sitewww.bortech.com.

Jan 1, 2004

By John Mitchell, Mark K. Jorgensen

Newmont Mining’s Ahafo Mine is located in Ghana approximately 300 km (190 miles) northwest of the capital city of Accra in the Brong-Ahafo region. The nearest city is Sunyani, located 45 km (28 miles) to the north. The Ahafo Mine will process ore from seven major pits that extend along a 40-km (25-mile) strike. Four pits are in the south and three pits are in the north. The resource is currently stated at 373 t (12 million oz). But it still has the potential for growth both from new discoveries and the development of underground operations.

Jan 1, 2007

By Steve Dubnewych

The Joint Water Pollution Control Plant, operated by the Sanitation Districts of Los Angeles County, treats wastewater generated by over three million people. A new tunnel and ocean outfall is being considered to meet future hydraulic demands and provide long-term redundancy for the Districts? existing tunnels, portions of which were constructed as early as the 1930s. The detailed process used to evaluate the feasibility of various tunnel and out-fall locations is described. Challenges include a geologic profile with mixed face and squeezing ground conditions; high water pressures; active fault crossings; gassy and contaminated ground conditions; and liquefaction, slope stability, and lateral spreading concerns in the area of the riser and diffusers.

By W. J. Kennedy, John D. Gardner

Introduction During the past 10 years, energy costs in mining have risen from about 4% to as much as 25% of total production cost. When combined with declining ore grades, these costs exert inordinate stress on mine productivity. Industrial engineering techniques have traditionally been aimed at improving manufacturing facilities productivity, but they have been applied to mining as pressure for productivity improvement has increased. These techniques can perform four useful functions for mining operations by improving methods, equipment selection procedures, energy use through scheduling, and managing energy costs rather than being managed by them. This article discusses some of the standard techniques for productivity improvement, and how they can be adapted to perform these four functions. Pre-Production The best time to seek high productivity is when a mine is being planned. During pre-production, when most options are still open, an optimum mine design is achievable. At this time, major equipment selections are made, the layout, material handling systems, and processes are designed, and critical energy source decisions are made. By including explicit energy cost projections, decisions can be made that will save significant amounts of money per ton of ore over the life of the mine. Attention can also be given to often overlooked details such as lighting. Some of the same tools used in new mine planning are applicable to productivity improvements at an existing plant. These tools are the charting and modeling methods that have been developed by industrial engineers over the past 75 years. Energy Consumption Before any analysis of energy consumption can be performed, preliminary work is necessary to find the kind of energy used, how much it costs the plant, and when electrical peaks occur. Past bills should be examined to determine the monthly consumption rate and the cost of each energy type. These data should be adjusted to remove effects caused by production fluctuations or weather. Knowing when electrical peak demands occur is necessary because these determine either the electrical capacity needed or the amount that must be bought. At $500-$800 per kW for construction or $5-$15 per kW per month for purchase, they represent a significant cost. By the time these data are collected, planners should be aware of the importance of energy in the total cost of mine operation, and should have the most crucial time data for electrical peak demand. Flow Process Chart Reducing costs can be accomplished by a thorough look at mine systems and how altering one system causes changes in others. By developing and exercising models of production processes outward to the transportation of the final product, otherwise obscured weaknesses may become apparent. There are tools available for analyzing the mine and its associated systems; one of the most useful is the flow process chart. The flow process chart gives a system analysis of a production procedure by classifying all actions into one of five types: operations, inspections, transportation, delays without paperwork, and delays with paperwork. Operation: In an operation, the nature of something is changed. Examples are blasting, washing coal, and processing matter. Denoted by 0. Inspection: Examining an object for identification or to measure some attribute. Examples are determining whether a drill hole is deep enough, deciding how far to cut under an unsupported roof when operating a continuous miner, or checking the lubricant level on a truck. Denoted bye. Transportation: Moving an object from one place to another. Examples are transporting overburden, moving coal on a conveyor belt, and pumping water. Denoted by =>. Delay without paperwork: A delay that is an inherent part of the system. Examples include idle time of a continuous miner while waiting for shuttle cars or for roof bolting, crushed ore in a storage area waiting for grinding and flotation, and people from one craft waiting for another craft to finish. Denoted by D. Delay with paperwork: A delay that can be terminated only by some written authorization. Examples are coal that cannot be removed until authorized by a bill of sale and transportation orders, personnel records, maintenance, or spare parts. Denoted by V. In practice, the flow process chart is completed after data collection and a detailed examination of the process. Data collection is needed to answer questions on distance, quantity, and time for each of the operations. As the analysis is being performed, each step of the process is subjected to these questions: • Why is the step necessary? • What is being moved? • When does the step take place, and why?

Jan 11, 1983

By Michael Lenz

Predictive maintenance technologies including vibration analysis, tribology, infrared thermography, ultrasonic detection, and electrical measurements have been applied to large electric mining shovels. The predictive program was initiated on the P&H Model 2300 and 4100 electric shovels. The utilization of these technologies has shown the potential for improving electric mining shovel availability and minimizing maintenance costs. Predictive technologies provide the tools to assess machinery condition. Availability is enhanced by the condition based planning of component replacement. Maintenance costs are minimized by focusing resources through condition based prioritization.

Feb 24, 1997

By Jr. Matthews

The Candelaria copper-gold deposit is located in Region m of Chile, 805 kilometers north of the capital, Santiago. Candelaria was discovered in 1987, following a six month exploration program. In late 1986, induced polarization (IP) surveys outlined an anomalously high response within the area of interest. The first test hole bad three intersections totaling 49 meters, with an average grade of 1.97% copper. Drilling eventually outlined approximately 390 million tonnes, grading 1.09010 copper and 0.26 grams/tonne gold. Production began in early 1995 and is estimated at 120,000 tonnes copper and 80,000 ounces gold annually.

Jan 1, 1996

TABLE TUNNEL NAME OWNER LOCATION STATE TUNNEL USE LENGTH (FEET) WIDTH (FEET) BID YEAR STATUS Gateway Tunnel project Amtrak Newark NJ Subway 14,600 24.5 2015 Under study

Sep 1, 2013

By M. Moats

Copper electrowinning operations have dramatically improved their ability to produce high quality copper at low costs over the past several decades. Even so, some fundamental understandings are still lacking, which could allow operates to run more efficiently. For example, a rule of thumb exists that estimates a current efficiency loss of 2-3% per gram per liter of iron in the electrolyte. While several laboratory studies have been performed that demonstrate this rule of thumb is likely true, no definitive relationship exists. In this paper, the first steps in developing a definitive relationship are presented. The effective diffusivity of ferric ions in synthetic copper electrowinning solutions was measured using chronoamperometry and the Cottrell equation. The effective diffusivity of ferric ion was determined as a function of electrolyte concentration and temperature. Synthetic electrolytes were then used in laboratory scaled copper electrowinning experiments where relationships were found under stagnant conditions between current efficiency and solution composition.

Jan 1, 2009

By Ralph W. M. Lai

The liquid membrane separation process was first patented in 1968 for separating hydrocarbons.(1-4) This stimulated many researchers to join in the area of separating organic compounds. l Since then, its applications have been extended to the removal of contaminants from waste water,(12-33) encapsulation of enzymes and/or microorganisms for reaction and/or separation, (24-28) oxygenation of blood (artificial lung),(19) removal of toxins from blood (artificial kidney)(26,20) and metal extraction.(31-63) This paper discusses the possible process schemes for using liquid membranes to separate and concentrate copper ion from its acidic leaching solution.

Jan 1, 1982

By Francis J. Kiessling

Energy and the conversion of potential energy into alternate forms is becoming a topic of household conversation for a larger segment of the world's population as mankind's desire for products derived from the vast array of technological developments continues to expand. The world's use of steel and the high energy consumption related to the production of steel promotes an awareness of the limitations of existing technology and a search for more economical alternates. Terminology such as (BF) Blast Furnace, (BOP) Basic Oxygen Furnace, (EAF) Electric ARC Furnace, (DR) Direct Reduction, (DRI) Direct Reduced Iron and (FC) form coke is becoming commonplace as alternates are being sought to alleviate the energy crunch. Coke production by various methods was developed as early as the seventeenth century in Europe to replace the disappearing hardwood forests that supplied the initial blast furnace fuel in the form of charcoal. In 1880, the Semet Solvay by-product coke oven design was introduced to the United States at Syracuse, New York, to supply coke for use in the production of soda ash, coke oven gas and its by products as the primary source of many organic processes. Although the Semet Solvay coke oven has not been marketed for decades, these coke oven batteries are in use today producing metallurgical coke, coke oven gas, and related by-products.

Jan 1, 1980

By D. McSwain-Santos

Soda ash is the trade name for sodium carbonate, a chemical refined from the mineral trona or naturally occurring sodium carbonate-bearing brines (both referred to as natural soda ash) or manufactured from one of several chemical processes (referred to as synthetic soda ash). It is an essential raw material in glass, chemicals, detergents and other important industrial products. Production U.S. soda ash production during 2004 increased to10.9 million Mt (12 million st). Five companies comprised the domestic soda ash industry. Four were in Wyoming operating five plants. One was in California with one plant.

Jan 1, 2005