Optimizing Ore–Waste Dig-Limits as Part of Operational Mine Planning Through Genetic Algorithms

Dig-limit optimization is an operational decision making problem that significantly affects the value of open-pit mining operations. Traditionally, dig-limits have been drawn by hand and can be defined as classifying practical ore and waste boundaries suiting equipment sizes in a bench. In this paper, an optimization approach based on a genetic algorithm (GA) was developed to approximate optimal dig-limits on a bench, given grade control data, equipment constraints, processing, and mining costs. A case study was conducted on a sample disseminated nickel bench, in a two destination and single ore-type deposit. The results from using the GA are compared to hand-drawn results. The study shows that GA-based approach can be effectively used for dig-limit optimization.     

An evaluation of the relationship between physical/mechanical properties and mineralogy of landscape rocks as determined by hyperspectral reflectance

We investigated the relationships between mineral content and the physical and mechanical properties of landscape rock using a non-destructive remote sensing method applied in the laboratory. Using this technique, the spectral properties of the landscape rock could be collected at different wavelengths without harming the samples. Differences in spectral reflectance were compared with the physical and mechanical properties of the stone. Significant correlations were observed between reflectance values and the rocks’ mechanical and physical properties, with correlation coefficients of 95 to 99 %. However, establishing a correlation between two variables is not a sufficient condition to establish a causal relationship. Mineral densities and mineral content are characteristics used for the classification of landscape rock. We have concluded that although spectral signatures from landscape rock can be used for predicting which stones might have similar features when comparing two batches of stone, the high correlations we discovered cannot confirm a cause and effect relationship that would allow for the prediction of a rock’s physical and mechanical properties. Although this conclusion is disappointing, the mineral content and the significant correlations discovered by hyperspectral reflectance scanning can be used as supplementary information when comparing two samples of landscape rock.     

Three-dimensional supervirtual seismic refraction interferometry

Improved supervirtual interferometry (SVI) method that enhance the signal-to-noise ratio (SNR) of noisy seismic refraction data is presented. This 3D supervirtual algorithm is helpful in removal of side lobes caused by convolution in the conventional 3D SVI method. In this study, we extend the supervirtual seismic refraction interferometry method to 3D geometries commonly used in active seismic exploration. To achieve this objective, synthetic 3D seismic refraction data were created using single patch orthogonal geometry. Simple two-layers velocity model was used. A zero phase wavelet was convolved with the refraction travel time to create the seismic wiggle trace. The refraction arrival is computed using the equation for horizontal refractor case and is not adapted for dipping refractor. Noise of Gaussian distribution with zero mean and 0.25 standard deviation was added to simulate a case of moderate ambient noise. The supervirtual algorithm, consisting of crosscorrelation, alignment, summation, and first arrival calculation is performed. By aligning and summation of all the correlogram, the stationary position of source-receiver pairs as required in the 2D supervirtual method are eliminated in this case. Synthetic data presented in this study shows accurate first arrivals after the application of the 3D SVI and traces with much better SNR than the actual traces.     

Performance of seismic arrays in the presence of weathering layer variations

Near-surface layer variations can degrade the desired response of seismic arrays which are typically used to attenuate horizontally traveling coherent noise and enhance vertically traveling signal. We investigate the effect of variations in the near-surface layer thickness on the performance of arrays by studying their impulse and wavelet responses. The models considered include the topographic variations and a channel in the base of weathering layer. The topographic variations include a dipping surface layer as well as a surface layer that follows a sine wave. The geological channel is assumed to be present under the entire receiver array as well as partially under a few receivers. We use Ricker wavelet and model plane wavefronts with incidence angles (90, 70, 45, 20, and 5 °) on a 12-element equally weighted array for the weathering layer models. We found that the array responses are more degraded for near-vertically traveling waves in all cases. The array responses are also found to be more degraded when channel variations are present underneath a few receivers as compared to the entire array length. We recommend designing a spatial filter or using single-sensor records after correcting for intra-array statics to preserve the reflection amplitudes in the presence of weathering layer variations.     

Did satellite imagery supersede aerial imagery? A perspective from 3D geopositioning accuracy

In this study, the geometric accuracy comparison of aerial photos and WorldView-2 satellite stereo image data is evaluated with the different number and the distribution of the ground control points (GCPs) on the basis of large scale map production. Also, the current situation of rivalry between airborne and satelliteborne imagery was mentioned. The geometric accuracy of Microsoft UltraCam X 45 cm ground sampling distance (GSD) aerial imagery and WorldView-2 data both with and without GCPs are also separately analyzed. The aerial photos without any GCP by only using global navigation satellite system (GNSS) and inertial measurement unit (IMU) data with tie points give an accuracy of ±1.17 m in planimetry and ±0.71 m in vertical that means nearly two times better accuracy than the rational polynomial coefficient (RPC) of stereo WorldView-2. Using one GCP affects the accuracies of aerial photos and WorldView-2 in different ways. While this situation distorts the aerial photo block, it corrects the shift effect of RPC in WorldView-2 and increases the accuracy. By using four or more GCPs, ½?pixel (～0.23 m) accuracy in aerial photos and 1 pixel (～0.50 m) accuracy in WorldView-2 can be achieved in horizontal. In vertical, aerial photos have 1 pixel (～0.55 m) and WorldView-2 has 1.5 pixels (～0.85 m) accuracy. These results show that Worldview-2 imagery can be used in the production of class I 1:5000 scale maps according to the ASPRS Accuracy Standards for Digital Geospatial Data in terms of geometric accuracy. It is concluded that the rivalry between aerial and satellite imagery will continue for some time in the future.     

Constraints on unconsolidated pyroclastic flow sediments related REE enrichments originated from potassic-alkaline Gölcük stratovolcano: Darıdere-Direkli-Yakaören (DDY) table 4deposits,southwestern Anatolia of Turkey

Acta Geochimica - In the last five decades, Rare Earth Elements (REE) are mostly produced from carbonatite complexes and alkaline magmatic environments. In this respect, pyroclastic flows produced...     

Spatial analysis of water quality and its suitability in farming giant freshwater prawn (Macrobrachium rosenbergii) in Negeri Sembilan region,Peninsular Malaysia

Finding potential sites for resilient prawn production in the tropical environment that also prevents wastage of natural resources is not an easy task. The purpose of this study is to evaluate water quality suitability for prawn farming in Negeri Sembilan of Peninsular Malaysia based on Geographic Information System (GIS). To achieve this goal, numerous criteria including sources of water, water temperature, water pH, sources of pollution, salinity, soil texture and availability of phytoplankton criteria were considered for the modelling process. Analytic Hierarchy Process (AHP) technique was performed to standardize the criteria and the weighting process. The weighted overlay of indicators and results were accomplished by applying the Multi‐Criteria Decision Analysis (MCDA) method in GIS. It was indicated that the Negeri Sembilan area has potential for prawn farming. The results showed that about 25 per cent (163 056.93 ha) of the area was most suitable for prawn farming, about 58 per cent (384 656.88 ha) was considered moderately suitable, while 18 per cent (117 633.49 ha) was regarded as least suitable. The study concluded that the multi‐criteria decision analysis of water quality for prawn farming is vital for regional economic planning in the Negeri Sembilan area and also significant when establishing a model for aquaculture development.