Figure 1 - uploaded by Cem Sensogut
Content may be subject to copyright.
Source publication
In the case of coal stockpiles finding suitable environmental conditions, spontaneous combustion phenomenon will be unavoidable. In this study, an industrial-sized stockpile having a shape of triangle prism was constituted in a coal stockyard of Western Lignite Corporation (WLC), Turkey. The parameters of time, humidity and temperature of air, atmo...
Context in source publication
Context 1
... coal stockpile was formed at a stockyard of the WLC in Tuncbilek for the experimen- tal works. Coals produced from open pits of WLC (Figure 1) are enriched in Tuncbilek coal washeries. The size of the stockyard pile was about 10 m 5 m width, with height of 3 m; the mass being approximately 120 tons of coal in total. ...
Similar publications
The spontaneous combustion of lignite during microwave drying was evaluated with the focus on the effects of, for example, microwave power and output mode, the final temperature of the samples, and the oxygen content of the drying atmosphere on the moisture contents corresponding to the ignition (IMCs). This empirical study was performed using a la...
The spontaneous combustion liability of lignites with particle sizes of 35 and 200 mesh kept as
open and enclosed under laboratory environment at 30oC for duration of 16 weeks was determined.
Crossing Point Temperature Method (CPTM) was utilized for the spontaneous combustion susceptibility
of coal samples. The results obtained showed differences a...
Citations
... The finite element method simplifies a system by representing the granular solids as a continuum rather than as discrete particles, and the analysis may be either static or dynamic. The method can, therefore, provide global information such as quantifying stress distributions within a pile (Ai et al., 2011); static and dynamic silo wall pressures (Rotter, 1998); bulk velocity fields (Liu et al., 2019); or self-heating behaviour (Ozdeniz and Sensogut, 2008), but not at the scale of individual particles. ...
Stockpiles and bins are an integral part of mineral processing plants, and their operation plays a significant role in plant performance. In most materials-handling and storage facilities, size segregation is a common issue, which can have a severe impact on the performance of downstream processes. Despite its importance, the issue has not received enough attention. For coarse ore stockpiles, the size range is wide, but most of the existing research has focused on the segregation of binary systems. Therefore, understanding size segregation in stockpiles and bins is important, to address the issue of size segregation in the mineral processing industry. In this thesis, a three-dimensional dynamic stockpile/bin model has been developed, which can model the dynamic response of a stockpile/bin, including the materials height variation and the particle size segregation.
Laboratory-scale experiments were designed and conducted to quantify size segregation in stockpiles. The test results indicate that it is possible to quantify size segregation in the laboratory and scale up the results. The data generated will enable the modelling of size segregation in industrial-scale stockpiles. Whilst size segregation is a recognised factor in operating stockpiles, there is no mature index to quantify the degree of size segregation in multi-sized stockpiles. After reviewing the existing indices and identifying their strengths and limitations, three novel indices were proposed. The experimental results confirm that the proposed indices are suitable for quantifying the size segregation in a multi-sized stockpile and perform better than existing indices. The new size segregation indices can be utilised to quantify the segregation in stockpiles and provide information for predicting the performance of the downstream processes.
The Continuous Cellular Automata (CCA) modelling approach is utilised in the model. This method divides the volume of the stockpile/bin into a three-dimensional (3-D) grid of cells, with each cell containing an independent set of properties that can be tracked throughout the simulation. Size segregation during material flow, and trajectory segregation from the feed conveyor are incorporated into the model. The variation in the stockpile/bin surface profiles and the size distribution of materials exiting the feeders under the stockpile/bin can also be predicted. Laboratory-scale experimental results were used to calibrate the size segregation in the model, and the calibrated parameters were used for simulating industrial stockpiles.
Data collection was carried out at MMG’s Las Bambas operation in Peru. The Las Bambas concentrator produces copper concentrate, which also contains gold, silver and molybdenum. The concentrator consists of two parallel SAG mills, each followed by a ball mill in closed circuit with primary cyclones. Both lines are fed from a coarse ore stockpile (COS) with a live capacity of approximately 500,000 t of primary crushed ore. In this thesis, the results are presented of the analysis conducted on Process Information (PI) data and the analysis of the behaviour of the stockpile under different operating regimes. The results of the data analysis indicate that the size segregation in the stockpile has important impacts on the performance of the SAG mills. Data collected from the mine site were also used for the stockpile model validation. The simulation results showed good agreement with the industrial data, including the stockpile height variation and the particle size distribution in the feeders, indicating that the stockpile model can be used to predict the flow behaviour of the industrial stockpile. Several stockpile design and control scenarios were simulated using the stockpile model, and the simulation results provide ideas for the design and operation of future stockpiles.
The research carried out for this thesis fills a gap in the current knowledge concerning the modelling of a wide size range of stockpiles and bins with size segregation and contributes to the process design and control of the whole comminution circuit. This research will increase the understanding of stockpile and bin modelling in the industry and show the importance of modelling materials handling for process control and optimisation.
... Wind creates airflow through the coal stockpile enhancing the oxidation process, which in turn is affected by the diversity of compositions and properties of coal as well as its porous structure. A review of literature indicates numerical studies on the fluid flow and heat transfer by simulating coal as a porous material (Li, 2008;Ozdeniz and Sensogut, 2008;Sensogut, Kaufmann and Petit, 2002;Struminski and Madeja-Struminska, 2005). In these studies, coal is assumed to have constant physical properties (porosity and permeability). ...
... Struminski and Madeja-Struminska (2005) presented a method to determine the approximate temperature of arising spontaneous fire centre and the time of coal self-ignition. Ozdeniz and Sensogut (2008) experimentally investigated the effect of time, humidity, air temperature, air velocity and direction on the coal stockpile. A number of experimental and theoretical studies have shown that the variation of porosity near a solid boundary has a significant effect on the velocity fields in packed beds (Vafai, 1984(Vafai, , 1986Vafai, Alkire and Tien, 1985). ...
Spontaneous combustion occurs in stockpiles in coal managements and causes interruptions in production and economical and environmental problems. This work was performed on an industrial-scale stockpile formed with +18-mm clean coal. The temperature changes of the stockpile exposed to suns rays were measured. Concurrently, the values of solar intensity, air temperature, air pressure, air humidity, wind speed, and wind direction affecting the stockpile were measured continuously. A statistical model to predict spontaneous combustion was developed by multi-nonlinear-regression analyses. The correlation coefficients were calculated around 0.95 levels. With this model, the effects of atmospheric conditions on spontaneous combustion of coal stockpiles can be predicted.
