Lifetime Of Mine Research Articles

Assessment of mine slopes stability conditions using a decision tree approach

Continuous assessment of slope stability is important to the open pit design and operation. This article aims to present a tool for evaluating the stability conditions of rock slopes in mining, based on a global geotechnical database, using machine learning techniques. Different models are evaluated in this research: the general model, which uses all variables; the mathematical model, which uses only variables selected by the random forest (out-of-bag); and two expert-based models: the Q-Slope model and the Santos model. The validation of the model was done through the test sample, using partition confusion matrices aiming at reproducibility of the results. A study of the types of errors was carried out using Principal Component Analysis (PCA). The study of errors allowed the identification of samples that were inconsistent with the others. Afterwards, the models were redone and compared with the previous ones. The best performers are presented and discussed. The proposed methodology does not replace the classic analysis of slope stability. On the contrary, it contributes to engineers and geologists with a tool for monitoring the stability conditions of slopes in a mining operation. Slope stability analysis must be carried out throughout the mine's lifetime and, therefore, it is believed that the tool proposed here can optimize the selection of slopes most susceptible to instability.

Application of meta-heuristic optimization algorithm to determine the optimal cutoff grade of open pit mines

The optimal cutoff grade leads to maximizing the profit or the net present value (NPV). One of the most important issues in open pit mining is cutoff grade optimization with regard to NPV maximization over the mine life. The most famous method that applied for cutoff grade optimization is the Lane methodology. Mining capacity, concentration plant capacity, and refining plant capacity are the three major parts of the abovementioned methodology and further, more time value of money and ore grade distribution are considered in Lane method. Repeated and cyclic calculations are the most disadvantages of lane methodology and therefore, in this research, the imperialist competitive algorithm (ICA) as a robust meta-heuristic optimization method has been applied to calculate the optimal cutoff grade. The accuracy of calculation was set to 0.001% and also the production of each unit and the NPV have been determined by ICA method. The optimum cutoff grades have been obtained from 0.232 to 0.135% in mine life time and NPV was calculated 37,750 billion Iranian Rials but the range of cutoff grades that calculated by Lane method was from 0.233 to 0.155% and NPV was determined 37,434 billion Iranian Rials. The results of this study showed that the determination of the optimum cutoff grade by the ICA has high accuracy and more speed of calculation in comparison with traditional lane method.

Optimal mill cut-off grade modeling in the mineral deposits via MIP: Haftcheshmeh copper deposit

Cut-off grade play a critical role in defining tonnages mined and processed, average grade of mill feed, cash flows, mine life time, and all major characteristics of a mineral deposit. Simply, the cut-off grade is the lowest grade at which material is considered ore and is processed to create a concentrated commodity product. Essentially, it asserts that the mill cut-off grade is a function of the ore availability and the needs of the mill. The focus of this paper is upon one of these long time-scale decisions: whether to process the extracted material, or to waste it. Consequently, an effort is made for the development of a model for optimization of mill cut-off grade which considers grade blending of mineral deposit. A new mixed integer programming (MIP) model is proposed to deal with this objective and with this model determined the mill cut-off grade of Haftcheshmeh Copper deposit. The results show the obtained mill cutoff grade from proposed model generates the optimum average grade. Therefore, generated net value (NV) from this model is nearer to reality.

Estimation of Vertical Distance and Reduce Level using Modern Mine Survey Equipments (Total Station) at Sub Level in Maddhapara Granite Mine, Bangladesh

An underground mine survey work is done using Total Station (TS) at sub-level from third drilling drift to cage shaft in Madhyapara Granite Mine (MGM). The MGM is situated at Madhyapara in Dinajpur district, NW Bangladesh. Room and pillar sub-level stoping underground mining method is applied in MGM and extracted economic mineral ( granite, granodiorite, diorite etc) from five stopes, three in the northern side and two in the southern side. Different types of survey equipments (measuring tape, normal staff, compass, ranging rod, automatic level, automatic theodolite) were used in MGM during the development period for the constructions of shafts, underground roadways, drilling drifts, sumps, loading bunkers, cross cuts, stopes etc. MGM contains two vertical shaft (Cage Shaft and Skip Shaft) and three underground levels, ventilation level is used for mine air ventilation, sub-level is for drilling or blasting and production level is for production of mineral ores. The dimension of each stope (l×h×w) is 276,000 m 3 (230 m × 60 m × 20 m) as per design. Modern surveying in MGM reduce the error survey data which were used to develop the further constructions as per design and also monitor the weak zones or mine subsidence rate to minimize mine accidents. During the year of 2008-2009, an underground mine survey work is done and calculate the Reduce Level (RL) at various points. The first R.L in the mouth of third drilling drift is -247.267 m and last RL near the cage shaft is -246 m. The vertical distance is also calculated with taping method from surface (mean sea level) to ventilation level, sub level and production level is -228 m, -246 m and -270 m respectively. Using TS and other modern survey accessories regularly in MGM may give the actual survey results which may monitor all the mine constructions and find out the weak zones (if detect) and recommends for supporting system as per geotechnical pressures and finally MGM get read of any type of mine accidents and successfully continue as the mine life time.