Leszek Jurdziak

Study on Tracking the Mined Ore Compound with the Use of Process Analytic Technology Tags

The growing need of reducing the use of raw materials and energy in the chain of supplying goods draws the attention to all aspects of the most energy intensive processes like mining and processing of metal ore. Processing of raw materials strongly depends on their parameters, hence the more accurate identification of them should improve the process efficiency. The Process Analytic Technology with information carrying tags (pellets), annotating transported or processed raw material – is investigated within the DISIRE project. The application of DISIRE PAT for non-ferrous minerals processing is dealt with the copper producer KGHM S.A. The ore exploited in its underground mines in Poland is among the most difficult for processing. The ore compound is recognized in-situ – in mining faces. On the way to processing plants down the transportation system consisting of belt conveyors and ore bunkers, the portions of ore from numerous mining faces are converted into an unknown mixture. The study of PAT tags implementation to assign the conveyed ore with the relevant information to recognize the mixed ore compound is presented.

Autocorrelation Analysis of Cu Content in Ore Streams in One of KGHM Polska Miedż S.A. Mines

Information about ore quality along its route from its source – the deposit, through long and complicated belt conveyor system till processing plant is not available in KGHM Polska Miedz on a daily basis. There were only few papers which analyzed variability of Cu content in feed to processing plant, on the transfer conveyor linking two mines and on the selected sectional conveyors. There were no such analysis regarding variation of ore lithological compositions. Such knowledge should improve metal recovery and reduce energy in processing plant by adjustment of milling and ore beneficiation parameters to known in advance copper ore quality data. Lack of data about ore composition prompted authors to analyze autocorrelations of Cu content time series in ore streams on the section and transfer conveyors as well as in the feed to processing plant. Determined differences in range of significant autocorrelations in ACF and PACF in different places along belt conveyor route have been explained by increasing difficulties in changing the average content of copper in ore coming from the growing area and a range of routes of loading machinery and face advance in comparison to range of directional semivariogram. The planned DISIRE experiment with application of Process Analyser Technology (PAT) sensors (containing ore information pellets), dropped into the transported ore streams and simulations of real flow of ore stream should show possibility to predict ore quality in advance to give enough time for necessary adjustments.

Condition-Based Conveyor Belt Replacement Strategy in Lignite Mines with Random Belt Deterioration

In Polish lignite surface mines, condition-based belt replacement strategies are applied in order to assure profitable refurbishment of worn out belts performed by external firms specializing in belt maintenance. In two of three lignite mines, staff asses belt condition subjectively during visual inspections. Only one mine applies specialized diagnostic device (HRDS) allowing objective magnetic evaluation of belt core condition in order to choose the most profitable moment for the dismantling of worn out belt segments from conveyors and sending them to the maintenance firm which provides their refurbishment. This article describes the advantages of a new diagnostic device called DiagBelt. It was developed at the Faculty of Geoengineering, Mining and Geology, Wroclaw University of Science and Technology. Economic gains from its application are calculated for the lignite mine and for the belt maintenance firm, taking into account random life (durability) of new and reconditioned belts (after the 1st and the 2nd refurbishment). Recursive calculations for following years allow the estimation of the length and costs of replaced, reconditioned and purchased belts on an annual basis, while the use of the Monte Carlo method allows the estimation of their variability caused by random deterioration of belts. Savings are obtained due to better selection of moments (times) for the replacement of belt segments and die to the possibility to qualify worn out belts for refurbishment without the need to remove their covers. In effect, increased belt durability and lowered share of waste belts (which were not qualified for reconditioning) create savings which can quickly cover expenditures on new diagnostic tools and regular belt inspections in the mine.

Random Loading of Blasted Ore with Regard to Spatial Variations of Its Actual Lithological Compound

The simulation model of the mine transportation system with regard to actual parameters of haul truck inter-arrival times was built in FlexSim. Haul trucks classified by their payload were sampling the rock material from corresponding mining faces. Two main simulation variants (V1 and V2) with a constant overall or mining face specific copper content and lithology were analyzed. The new algorithm was developed, based on the random sampling of lithologic factions from the muck pile by haul trucks. The variant V2b illustrates the interesting feature of this algorithm, when first more material from the bottom layer of the mined seam was drawn, causing the depletion of its deposit in the subsequent haul truck courses. The study demonstrated that both approaches can be used interchangeably to simulate the economic outcome of the metal production on the hourly basis. The difference between V1 and V2 variants in the total amount of copper produced after full simulation cycle changes linearly with the amount initially blasted rock mass declared in the V2 variant. The algorithm allows to choose the maximum amount of rocks to be blasted that can be delivered to the OEP in a given time.

Conveyor Belt 4.0

Industrial revolution known as Industry 4.0 is present in all branches of industry and in all areas of production. It also stimulates changes in the mining industry, known as Mining 4.0. Transportation processes have a significant impact on the technological chain, from the working of minerals to the selling of the final products. Continuous transportation with the use of belt conveyors allows cost reductions and increased range. It also allows fully automatic operation as well as remote monitoring and control from the centralized control room. Presently, the conveyor belt is the least sensor-monitored system in Polish mines. This paper demonstrates that appropriate methods and devices for the monitoring of conveyor belts and splices already exist. Polish mines have been collecting and recording data on the installed belts, splices and repairs. The authors propose to introduce diagnostic systems and integrate data from a number of sources in order to include the idea of conveyor belt 4.0 into the digitally controlled conveyors 4.0, and – in wider perspective – into the Mining 4.0 intelligent solutions.

Analysis of Moving Averages of BWEs Actual Capacity

Analysis of productivity data from different lignite mines leads to the conclusion that theoretical BWE capacity is utilized only in a small percentage. Therefore, it is possible to achieve a substantial reduction of energy consumption by optimal dimensioning of BWEs and belt conveyor parameters to actual loads generated during the cyclical excavation of subsequent slices, terraces, blocks, and benches. Based on the analysis of BWEs efficiency and time series of their actual volume capacities in a Polish opencast lignite mine, it is proposed to apply the Extreme Value Theory (EVT) for dimensioning belt width and for selecting required power of conveyor drives. The asymptotic decrease of high order percentiles of actual capacity averages with the increase of loading time (the length of receiving conveyors) shows that there is a big potential for energy savings.

Random Deterioration Process of Conveyor Belt Evaluated by Statistical Analysis of Core Failures Detected Along Belt Axis and Elapsed Time

Magnetic diagnostic methods are used for steel cord belt condition evaluation since the beginning of 1970s. Initially they generated an analogue signal for several tens of centimetres of conveyor belts scanned sequentially with one measuring head in several cycles or the whole width of the belt at one time thanks to the installation of many measuring heads across the entire cross section. This did not allow identification of single centimetre failures, but rather an aggregate assessment of the state of quite wide waist. Modern diagnostic devices, thanks to miniaturization, allow up to 200 heads per belt width to identify damage of individual cords. Instead of analogue signals, they generate a zero-one digital signal corresponding to a change in the magnetic field sign, which can illustrate damage on 2D images. This makes it easier to identify the location and size of the damage in the belt image. Statistical analysis of digital signals summed up for consecutive sections along the belt axis allows to present both the source signal and its aggregation for band of a given width to form aggregate measures of belt damage such as the damage density per 1 meter of belt. Observation of changes in these measurements at different times allows on evaluation of its rate of change over time, which can be used to forecast future belt condition and to select the proper moment of preventive belt replacement to another one to avoid emergency downtimes (egg in underground mines) or to recondition of belts (egg. in lignite surface mines). The paper presents the results of investigations of the damage condition of a core of a single belt segment working in one of the copper ore underground mines. Scanning of the belt condition was performed few times at intervals of several months. The paper presents the results of the analysis of the changes in core condition, showing the random character of the damage process along the axis and its change over time.