Mine In Turkey Research Articles

Evaluation of ground vibration effect of blasting operations in a magnesite mine

Ground vibrations induced by blasting are one of the fundamental problems in the mining industry and may cause severe damage to structures and plants nearby. Therefore, a vibration control study plays an important role in the minimization of environmental effects of blasting in mines. This paper presents the results of ground vibration measurement induced by bench blasting at Magnesite Incorporated Company (MAS) open pit mine in Turkey. The scope of this study is to predict peak particle velocity and to determine the slope of the attenuation curve for this site. For this purpose, the blasting parameters of 43 shots were carefully recorded and the ground vibration components were measured for each event. After carrying out statistical analysis, the site specific parameters were determined to predict the peak particle velocity. In the light of this analysis, the prediction graphics of maximum charge weight per delay versus distance for different damage criteria was proposed to be able to perform controlled blasting in order not to damage to the nearby structures, especially to the plant where rotary and shaft kilns have been established.

Stochastic modeling of accident risks associated with an underground coal mine in Turkey

In this study, a methodology is proposed towards development of an uncertainty model that includes randomness in the occurrence of days-lost accidents in a coal mine. The accident/injury data consists of 1390 days-lost accident cases recorded at GLI-Tuncbilek underground lignite mine from January 1994 to December 2002. In the first step of proposed methodology, the frequency and the severity of the accidents have been modeled statistically by fitting appropriate distributions. The test done by BestFit software yields a chi-square value of 21.53 ( p = 0.089) with 14 degrees of freedom and estimates the parameter of lambda for Poisson distribution as 12.87 accidents/month. For the severity component, a lognormal distribution is fitted to days-lost data and chi-square goodness-of-fit test calculates a value of 40.44 ( p = 0.097) with 30 degrees of freedom. The parameters of lognormal distribution are estimated as a mean of 14.3 days and standard deviation of 23.1 days, respectively. Then, two distributions are basically combined by Monte Carlo simulation in order to construct relative risk levels in yearly base referring to the final cumulative distribution. Finally, a simple forecasting modeling is carried out in order to quantitatively predict the expected risk levels by using decomposition technique in time series analysis. Stochastic model estimates that although, there would be substantial reduction in the expected number of accidents in the near future, the higher level of risks still should be a concern for the mine management.

Environmental impacts of bench blasting at Hisarcik Boron open pit mine in Turkey

This paper presents the results of ground vibration measurements carried out in Hisarcik Boron open pit mine located on the west side of central Anatolia near Kutahya province in Turkey. Within the scope of this study to predict peak particle velocity (PPV) level for this site, ground vibration components were measured for 304 shots during bench blasting. In blasting operations, ANFO (blasting agent), gelatin dynamite (priming), and delay electric detonators (firing) were used as explosives. Parameters of scaled distance (charge quantity per delay and the distance between the source and the station) were recorded carefully and the ground vibration components were measured for all blast events using two different types of vibration monitors (one White Mini-Seis and one Instantel Minimate Plus Model). The absolute distances between shot points and monitor stations were determined using GPS. The equation of square root scaled distance extensively used in the literature was taken into consideration for the prediction of PPV. Then, the data pairs of scaled distance and particle velocity obtained from the 565 event records were analyzed statistically. At the end of statistical evaluation of the data pairs, an empirical relation which gives 50% prediction line with a reasonable correlation coefficient was established between PPV and scaled distance.

Spoil pile instabilities with reference to a strip coal mine in Turkey: mechanisms and assessment of deformations

With the increasing adoption of the surface mining of coal, problems associated with spoil pile instability, which affects resource recovery, mining cost, and safety and presents environmental hazards, have become a matter of prime concern to mine planners and operators. The study of geotechnical aspects is thus very important in the rational planning for the disposal, reclamation, treatment and utilization of spoil material. A strip coal mine, one of the largest open pit mines in Turkey, is located in Central Anatolia and provides coal to a thermal power station. Coal production is carried out in two adjacent open pits, the Central Pit and South Pit. A large-scale spoil pile instability over an area of 0.3 km2 occurred within the dumping area of the Central pit. In addition, small-scale movement occurred in the outside dumping area. This paper outlines the results of field and laboratory investigations to describe the mechanisms of the spoil pile instabilities and to assess deformations monitored over a long period following the failure. Shear test results indicate that the interface between the floor and spoil material dumped by dragline has a negligible cohesion and is the most critical plane of weakness for spoil pile instability. Back analyses based on the method of limit equilibrium and the numerical modelling technique, and observations in the pit revealed that failure occurred along a combined sliding surface consisting of a circular surface through the spoil material itself and a planar surface passing along the interface between the spoil piles and floor. The analyses also indicated that pore water pressure ratios of about 0.25 satisfy limiting equilibrium condition and that rainfall about one month before the failure may be a contributing factor to the instability. Movement monitoring data obtained following the failure over a 1.5-year period suggested that the ongoing deformations were mainly due to compaction of the spoil material. Based on the monitoring data and the results of the analyses, the failure mode of the local instability occurring at the outside dumping area was considerably similar to that of the large instability.

Managing cyanide: health, safety and risk management practices at Turkey's Ovacik gold–silver mine

This paper discusses issues of cyanide management at the newly-constructed Ovacik gold–silver mine in Turkey. The mine, which has been using 120 ton/y of sodium cyanide (NaCN) since May 2001, was the first operation in the country to use cyanide to recover gold. Mine staff strives to continuously plan and provide detailed accounts of the management practices and initiatives being undertaken with regard to handling cyanide. It is believed that the programs and activities that have been implemented at Ovacik will facilitate improvement in this area.

Effects of circumferential pick spacing on boom type roadheader cutting head performance

Abstract Effects of equal and unequal circumferential pick spacing on the performance of boom type roadheaders having cylindrical cutting heads are investigated. For this purpose, two experimental cutting heads with equal and unequal circumferential spacing are designed and manufactured. The cutting head with unequal circumferential spacing is specifically designed to prevent tool-holder overlap at the nose section. Manufacturing difficulties associated with equal circumferential pick spacing due to tool-holder overlap are discussed with solid modeling and practical applications. The heads are tested at Park Cayirhan Coal Mine in Turkey and their cutting performances are analysed. Although better cutting performance for equal circumferential spacing are predicted by force–balance analysis, in situ measurements of instantaneous (net) traversing speed and cutting rate, pick consumption rate and machine vibration show that no significant difference exists between the performances of the two cutting heads.

Sulfur-isotope distribution and contamination related to the Balya Pb?Zn Mine in Turkey

Sulfur-isotope (δ34S) values and weight (%) of acid-volatile sulfur (AVS), chrome-reducible sulfide (CRS), elemental sulfur (ES), and acid-soluble sulfates were determined in Balya Mine ore rock, mine wastes, and Kocacay River and Lake Manyas sediments. Estimation of isotopic fractionation (Δ34S) between product sulfate and initial CRS (pyrite) was used to evaluate the progress of sulfide oxidation in the mine-waste area. Water- and acid-soluble sulfate produced from different mine-waste samples, such as metallurgical waste (MW) and waste rock (WR), in laboratory experiments also shows distinct δ34S values and allows identification of the acid-mine-drainage sources in the mine-waste area. Average δ34SSO4values are −1.43‰ for MW (n=4) and +2.06‰ for WR (n=8). Short (24 hr) and long (60 days) term leach experiments were considered using alternating wet/dry conditions to simulate sulfate-production capacity and metal-discharge characteristics for MW and WR piles. Release of heavy metals follows the order of Pb2+ >Mn2+ >Zn2+ >Cu2+ for these pile samples. Values of δ34SSO4 for river water that was collected after 3–4 h of heavy rainfall are close to values of δ34SSO4 for water-soluble sulfates from mine-waste piles used in laboratory leach experiments.

A Unified Relocatable SVC for Open-Cast Lignite Mining in Turkey

Design and implementation of a unified, relocatable static VAr compensator (SVC) meeting the reactive power compensation needs of various coal enterprises of Turkey for open-cast lignite mining are presented. Design and sizing of SVCs are based on mains data for all possible connection points, load bus data recorded in the field, monthly electric bills, and simulations carried out on PSCAD/EMTDC, SPICE, and MATLAB. In addition to standard ac/dc converter and motor tools used in the modeling of electric excavators, actual load characteristics obtained from data collected in the field by means of a data acquisition system have been processed in PSCAD/EMTDC to find out reactive power demand of each load bus, and to optimize sizing of the SVC within the power-factor penalty limits imposed by electricity authorities. The SVC component ratings have been based upon the suitability to all possible loads under worst operating conditions, thus making sure that they can be operated for different loading conditions, minimizing stock requirements, and inspection and maintenance costs. The implemented systems are flexible and extendable in order to meet the future needs of coal enterprises.

An Interpretation of the Effects of Using Different Delay Intervals in Blasting at an Open-Cast Mine in Turkey

An Interpretation of the Effects of Using Different Delay Intervals in Blasting at an Open-Cast Mine in Turkey

Photoelectrochemical power, chemical energy and catalytic activity for organic evolution on natural pyrite interfaces.

Natural pyrite (FeS2) has frequently been discussed as a material involved in CO2 fixation in presence of H2S and as a possible catalyst for the origin of life. A straightforward chemical fixation of carbon dioxide as proposed by Wächtershauser could not be verified from thermo-chemical equilibrium calculations by minimizing Gibb's Free Energy in the system C, O, H, S, Fe and appears unlikely due to the experimentally encountered large overpotentials involved in CO2 fixation. However, the hypothesis, by W. R. Edwards, that pyrite in shallow coastal waters may have been involved, can be sustained. In this case, daily available photoelectrochemical power from FeS2/Fe2+/3+ interfaces could have made the difference in combination with electrochemical processes, such as hydrogen insertion, and the solubilization of pyrite by the amino acid cysteine to yield dissolved chemical energy. Periodical changes in energy supply could also have entrained primitive self-organization processes for organic-biological evolution. Natural samples from thirteen ore deposits have been investigated photoelectrochemically. Efficient light-induced current generation has been found with several of these samples so that photoelectrochemical processes generated by pyrite have to be considered as naturally occurring phenomena, which could have been even more pronounced in oxygen deficient environments. Pyrite from the Murgul mine in Turkey of suboceanic volcanic origin was closer examined as a model system to understand the morphology and chemistry of pyrite photoactivity.

Analysis of ground vibrations caused by bench blasting at Can Open-pit Lignite Mine in Turkey

The principal disturbances created by blasting in open-pit mines are vibrations, air blast and fly rock. All of these problems, under some circumstances, may cause severe damage to structures nearby and, apart from that, these can be the possible sources of permanent conflict with the inhabitants who live close to the operation. Therefore, a vibration-control study was performed in mines on the basis that prediction of ground vibration components is of great importance in minimising environmental complaints. This paper presents the results of ground-vibration measurements induced by bench blasting at Can Open-pit Lignite Mine, which is located close to the residential area of Can town. Within the scope of this study, in order to predict peak particle velocity and determine the slope of the attenuation curve for this site, ground-vibration components were measured for blast events. During the study, the parameters of scaled distance were recorded carefully, and the ground-vibration components were measured by suitable monitors for 54 blast events. At the end of the evaluation of data pairs, an empirical relationship, which gives the average line at a 95% confidence level and an upper bound 95% prediction line with a good correlation coefficient, was established and suggested for this site.

EFFECTS OF CUTTING HEAD MOTION ON THE BOOM LENGTH OF ROCK AND COAL CUTTING MACHINES

Cutting heads or cutting drums employing drag tools, perform the cutting action either in traversing or arcing motion. Laboratory rock cutting investigations on simulating roadheaders cutting head operating in traversing motion, showed that the pick forces were proportional to the cross-sectional areas swept by these picks. Theoretical analysis of these investigations indicated that under equivalent conditions, these areas were greater for arcing motion, and thus the pick forces became inversely proportional to the boom length. A number of in situ trials were also conducted with roadheaders of various types at OAL Mine in Turkey to evaluate the practical significance of the laboratory findings. Both the laboratory and the in situ trials indicated that within the size and the capacity of the current machines, a variation in the boom length does not significantly affect the cutting speed or the advance per revolution of the cutting head. It was however shown that if the effective boom length is around 2 m or less, together with the advance per revolution being in excess of 0.05 m, an axial type cutting head may perform better when in traversing mode. Furthermore, the concept suggesting that in arcing mode, smaller tilt angles are the case for corner cutting tools, was found to have no practical significance.

Preparatory bioleaching to the conventional cyanidation of arsenical gold ores

Cyanide leaching is the wide-spread process for the extraction of gold from primary raw-materials. However when gold is associated with metal sulphides, an oxidative thermal or a chemical pretreatment is often needed to access precious metal particles. Bacterial oxidative leaching may be an interesting alternative — low cost and environmentally friendly — to liberate gold from the sulphide matrix and then make it amenable to cyanidation. Bioleaching with Thiobacillus ferroxidans has been investigated at 30°C at bench scale on a gold-bearing arsenopyrite (2 g/t Au) ore coming from Golcuck Mine in Turkey. The study was concerned with the influence of the age of the inoculum, pH, pulp density and time of the bacterial leaching at 30°C on the recovery of gold during the subsequent standard cyanide attack. Direct cyanide leaching of the arsenopyrite ground to −74 μm showed no gold dissolution at all, but with fine grinding to −30 μm, gold recovery increased to about 55.3% after 48 hours of cyanidation. On the contrary, cyanidation performed for 2 days on a bioleached arsenopyrite allowed 90% of gold to be solubilized in 2 hours.

Design aspects of cemented aggregate fill mixes for tungsten stoping operations

The use of cemented aggregates in fill practice has increased in recent years. Its effectiveness in fill design is widely accepted. In order to maximize its economy a rational approach to the mix design is essential. The purpose of the paper is to provide a basis for design of cemented aggregate fill mixes. The proposed method is based on data obtained from experimental investigations conducted for Uludaĝ Tungsten Mine in Turkey.

Relationship between geological, geophysical and geochemical data obtained from blind lead-zinc mineralization at Keban, Turkey

Abstract The Keban Pb-Zn deposit is an old and important mine in Turkey, and intensive geological, geophysical exploration and diamond drilling have been carried out in the area in an attempt to find new ore reserves. Graphitic schist in the hanging wall of the ore zone, which has sealed the deposit, has produced many false geophysical anomalies. Thus, it is apparently difficult to distinguish the geophysical anomalies related to ore deposits from those caused by the graphitic schist and other geological features of the area. Geochemical data obtained from soil samples over the deposite show significant leakage anomalies indicating the mineralization at depth. The geochemical data are also helpful in the interpretation of geophysical data.