Simulation-based decision-making system for optimal mine production plan selection

Price uncertainty is one of the major uncertainties in the life of mine (LOM) planning process which can have a decisive effect on the overall profitability. Today’s mine planning software tools provide block-sequencing optimisation for a given static price assumption that is then used as a basis of managerial decision-making process. This paper proposes a complementary approach to this by introducing a simulation-based decision-making tool that, with the help of simulation, seeks for the optimal mine plan when a managerially estimated price development with minimum and maximum boundaries is used as a data input for the given period. To demonstrate the approach, a realistic gold mine case study is presented with five alternative and technically feasible mine plans calculated in a static optimiser from a commercial mine planning software package. These mine planning scenarios are then subjected to price uncertainty in simulation with and without a price trend assumption to highlight the effect of price on the mine’s expected performance. Based on the results, we derive and demonstrate a simulation-based system that automates the matching of optimal mine plan with the managerial insight of long-term price development.

Habitat Mapping for Ecosystem-Based Management of Deep-Sea Mining

Spatial considerations are important at multiple stages in the development of a deep-sea mining (DSM) project, from resource definition, to identification of preservation and management zones within a contract area, to planning of suitable ecological strata for baseline studies and impact assessment, to mine planning and adaptive management. Large investments are made to collect remote sensing data early in exploration to support geological resource studies, but environmental considerations are often instigated at later stages of exploration and can become disconnected from spatial frameworks. We outline a process of harmonizing the environmental and geological aspects of DSM project development by incorporating a habitat approach early in the development cycle. This habitat approach supports ecosystem-based management, which is a central requirement of environmental assessments. Geostatistical techniques are described that are used alongside a hierarchical classification scheme to describe and map geoforms and substrates. This foundational habitat model can form the basis of spatially explicit ecosystem models and can inform sampling design and spatial planning at critical junctures of a project development, ensuring that sampling campaigns are connected by an ecosystem logic early in the cycle. We provide an example application from the NORI-D polymetallic nodule exploration contract area in the Clarion-Clipperton Zone.

Image segmentation methods for quick characterization of ore chip using RGB images

The ability to forecast geometallurgical properties during resource extraction is essential to optimize the mine to mill process. Models for mine planning thus often incorporate attributes related to processability. The analysis of these attributes in a laboratory can be time- and cost intensive. Only a limited number of data may be available. During production, grade control drilling may provide access to many more samples. Conducting laboratory analysis to each of these samples would be not realistic. If there was an opportunity to quickly obtain related proxy data, as physical characteristics that can stand in for direct measurements, then these indices could be estimated, certainly less precise but with a significantly increased spatial density. A moderately simple approach to acquire data from grade control drilling is to take digital Red, Green and Blue spectral bands images (RGB images) in from core trays. Although these capture only three spectral band regions, images can contain valuable texture and colour related information. A first necessary step is to automatically extract from an image and analyse objects, that represent ore particles or mineral content. This study aims to investigate the performance of different available segmentation methods under field conditions. First an overview of methods for image segmentation as a basis to create objects is presented. Objects can be related to single grains and minerals within the grains. The aim is to provide a basis for texture feature extraction related to granular rock, such as found in chip trains. Modern image analysis provides a large number of methods for segmentation and classification of objects. This work focuses on evaluating performance on images of 3 levels of complexity of pixel- based segmentation for complex or less noisy images and object-based segmentation (Watershed, Simple Linear Iterative Clustering and Quickshift) as a more advanced and universal method.

Use of an Adaptive Management System to Minimize Impacts of Deep-Sea Nodule Collection

In the nascent deep-sea mining industry, there is currently a high degree of uncertainty about what impacts prolonged metal extraction will have on the receiving environment. There is also concern regarding the transparency and monitoring of operations since the target environment is extremely remote and inaccessible. Polymetallic nodule collection is being pursued, which is distinct from other forms of deep-sea mining in that the resource is distributed in a thin layer atop the seabed, unlike cobalt-rich crusts or massive sulfides, which are concentrated in specific areas. The second distribution of nodules provides opportunities for dynamic mine planning not available for other mineral sources as many constraints normally affecting mining operations like waste stripping or underground development are absent. Also, the highly mobile ship-based collection system that utilizes robotic collectors is easily relocated to other areas in response to emerging data on environmental constraints such as proximity to fragile habitats, sensitive species, or high cumulative impacts. An adaptive management system has been identified as a vital strategy to address scientific uncertainty of ecological impacts of deep-sea mining. The design features dynamic mine planning, scenario modeling, and impact forecasting. Also, operating data will be transparently viewable in a publicly available dashboard. This paper describes an implementation of a threshold-based framework for an effective adaptive management system designed to leverage the unique characteristics inherent to the resource.

3D high-resolution seismic imaging of the iron-oxide deposits in Ludvika (Sweden) using full-waveform inversion and reverse-time migration

A sparse 3D seismic survey was acquired over the Blötberget iron-oxide deposits of the Ludvika Mines in south-central Sweden. The main aim of the survey was to delineate the deeper extension of the mineralisation and to better understand its 3D nature and associated fault systems for mine planning purposes. To obtain a high-quality seismic image in depth, we applied time-domain 3D acoustic full-waveform inversion (FWI) to build a high-resolution P-wave velocity model. This model was subsequently used for pre-stack depth imaging with reverse time migration (RTM) to produce the complementary reflectivity section. We developed a data preprocessing workflow and inversion strategy for the successful implementation of FWI in the hardrock environment. We obtained a high-fidelity velocity model using FWI and assessed its robustness. We extensively tested and optimised the parameters associated with the RTM method for subsequent depth imaging using different velocity models: a constant velocity model, a model built using first-arrival traveltime tomography and a velocity model derived by FWI. We compare our RTM results with a priori data available in the area. We conclude that, from all tested velocity models, the FWI velocity model in combination with the subsequent RTM step, provided the most focussed image of the mineralisation and we successfully mapped its 3D geometrical nature. In particular, a major reflector interpreted as a cross-cutting fault, which is restricting the deeper extension of the mineralisation with depth, and several other fault structures which were earlier not imaged were also delineated. We believe that a thorough analysis of the depth images derived with the combined FWIRTM approach that we presented here can provide more details which will help with better estimation of areas with high mineralization, better mine planning and safety measures.

3D reflection seismic imaging of the iron-oxide deposits in the Ludvika mining area (Sweden) using a focusing pre-stack depth migration approach

We present the pre-stack depth imaging results for a case study of 3D reflection seismic exploration at the Blötberget iron-oxide mining site belonging to the Bergslagen mineral district in central Sweden. The goal of this case study is to directly image the ore-bearing units and to map its possible extension down to greater depths than known from existing boreholes. Therefore, we applied a tailored pre-processing workflow as well as two different seismic imaging approaches, Kirchhoff pre-stack depth migration and Fresnel Volume Migration (FVM). Both imaging techniques deliver a well resolved 3D image of the deposit and its host rock, where the FVM image yields a significantly better image quality compared to the KPSDM image. We were able to unravel distinct reflection horizons, which are linked to known mineralisation and provide insights on lateral and depth extent of the deposits beyond their known extension from borehole data. A comparison of the known mineralization and the image show a good agreement of the position and the shape of the imaged reflectors caused by the mineralization. Furthermore, the images show a reflector, which is interpreted to be a fault intersecting the mineralisation and which can be linked to the surface geology. The depth imaging results can serve as the basis for further investigations, drillings and follow-up mine planning at the Blötberget mining site.

Evaluating Mine Design Alternatives for Social Risks Using Discrete Choice Analysis

As with other engineering design tasks, mine design involves setting design objectives and constraints (the feasible solution space) and finding the optimal design alternative. Mine engineers often struggle to incorporate the preferences of local community members into their evaluation of mine design alternatives because the mining literature lacks tools to quantify such risks during mine planning. This paper presents an approach to evaluate community acceptance (i.e., community preferences for the alternatives) using discrete choice models and decision-based design during mine planning. Using discrete choice models and a rigorous framework, engineers can estimate the cost of social risks as a function of the probability that individuals in the host community will prefer a particular design alternative. They can then estimate the overall utility of a particular design alternative to the project proponents. This paper illustrates the proposed approach with a strategic mine planning exercise for a gold mine. The framework can be a useful tool for designing mines for sustainability, if combined with effective community engagement and management’s commitment to creating shared value.

Optimising Productivity and Safety of the Open Pit Loading and Haulage System with a Surge Loader

The open pit mining load and haul system has been a mainstay of the mining industry for many years. While machines have increased in size and scale and automation has become an important development, there have been few innovations to the actual load and haul process itself in recent times. This research highlights some of the potential productivity and safety benefits that the incorporation of a surge loader may bring to the load and haul system through an analysis of the system, discussion of component characteristics, and mine planning aspects. The incorporation of the surge loader into open pit loading and haulage operations also enables improved safety. This is a result of a reduction in shovel–truck interactions and the reduced likelihood of truck overfilling and uneven loading. This paper details the number of mine worker deaths that a surge loader may have prevented within the Peruvian and Chilean mining industries.