Three-dimensional Block Model Research Articles

Ore dilution control when mining low-thickness ore bodies using a system of sublevel drifts

Purpose. The research is aimed at substantiating the optimal parameters of blast-hole ore breaking to reduce the rock mass destruction when mining low-thickness vein deposits using the mining system of sublevel drifts (SD). The focus is on analyzing the impact of blasting on the out-contour rock mass during the blast-hole breaking process. Methods. The three-dimensional block model is constructed using rating classifications of rocks based on studying their strength properties and structural peculiarities. The inelastic deformation zones around the stoping extraction are determined by numerical analysis using the finite element method in 2D formulation. Experimental blasts are assessed by varying the blast-hole drilling scheme depending on the stability rating. Findings. During the experimental-industrial tests, rational blast-hole drilling schemes have been substantiated, contributing to maintaining the stability of the host rocks when mining low-thickness veins. Originality. Effective methods for reducing the ore dilution have been substantiated, which take into account not only the strength properties and structural peculiarities of rocks, but also their seismic impact from blasting on the out-contour rock mass stability when mining low-thickness deposits using a system of sublevel drifts. Practical implications. Practical significance is in the possibility of minimizing the percentage of mineral dilution when mining low-thickness ore bodies using a system of sublevel drifts, which can significantly reduce the cost of mined minerals by reducing ore losses caused by the rock mass destruction during mining operations.

Два метода решения задачи планирования открытых горных работ

The article provides a general formulation of the open pit mining scheduling problem, described in the form of a three-dimensional block model and a set of requirements for the schedule. A brief overview of the two main methods for solving it as well as the main positive and negative aspects of these methods are given.

Easy profit maximization method for open-pit mining

A methodology applicable at any phase of a surface mining project for evaluating its current technical and economic feasibility is presented.It requires the typically available quantitative data on the ore-body, with its three-dimensional block model developed upon accurate interpolations. Thus it allows estimations of exploitable reserves in function of various cut-off grades, such as the average grade of mineable ore, the tonnages of ore and waste rock, stripping ratios and profit estimates for different production levels.If cost evaluations of essential mine operations are available (such as ore mining, waste removal, ore concentration, transportation, indirect project costs and expected concentrate selling prices), the methodology will provide clear indications on the economic feasibility of mining, including the best available options at any moment. Simple expressions are developed on the basis of a profit mathematical function and an application example is presented with data available from an existing iron ore deposit.

A simulated annealing approach to mine production scheduling

Increasing global competition, quality standards, environmental awareness and decreasing ore prices impose new challenges to mineral industries. Therefore, the extraction of mineral resources requires careful design and scheduling. In this research, simulated annealing (SA) is recommended to solve a mine production scheduling problem. First of all, in situ mineral characteristics of a deposit are simulated by sequential Gaussian simulation, and averaging the simulated characteristics within specified block volumes creates a three-dimensional block model. This model is used to determine optimal pit limits. A linear programming (LP) scheme is used to identify all blocks that can be included in the blend without violating the content requirements. The Lerchs–Grosmann algorithm using the blocks identified by the LP program determines optimal pit limits. All blocks that lie outside of the optimal pit limit are removed from the system and the blocks within the optimal pit are submitted to the production scheduling algorithm. Production scheduling optimization is carried out in two stages: Lagrangean parameterization, resulting in an initial sub-optimal solution, and multi-objective SA, improving the sub-optimal schedule further. The approach is demonstrated on a Western Australian iron ore body.

The conceptual ground model

The range of possible subsurface conditions that can be predicted, knowing the geological processes that formed the ground beneath a site, is self-evident to the geological or geotechnical advisor. This information underpins the conceptual ground model. Many construction cost over runs are caused by unforeseen ground conditions. Avoiding this requires a better desk study and ground investigation (including geophysical survey), as well as the development of a ground model that includes the known and suspected features on, below and adjacent to an engineering site. Such a model will assist in identifying the likely implications of the ground for a proposed engineering project. It is helpful to portray the conceptual ground model as a threedimensional block model that allows the scale of the features, in relation to the size of the project, to be appreciated. In addition, the geology should be characterised in engineering terms by the geological/geotechnical advisor, which means that geotechnical properties and their likely lateral and vertical variation, must be assessed within the context of the model. The difficulty in understanding the ground conditions at a construction site has its origin, in part, in the way that geological knowledge advances. Geological mapping has been carried out in Britain since the late 18th century when the canal network was constructed. The process of updating British geological maps is still continuing (see CIRIA Special Publication 149, A guide to British stratigraphical nomenclature, Powell 1998). The geologist has to interpret the information as it is made available from boreholes, trenches and

A micromechanical model of the cochlea with radial movement of the tectorial membrane

The function of the tectorial membrane in the cochlear micromechanics is uncertain. In modeling approaches some models have assumed it to be a resonator that participates in the sharp tuning mechanisms of the cochlea with its mass coupled to the ciliary stiffness of outer hair cells, being driven by the shear force between the reticular lamina and itself. This paper presents a different type of micromechanical model which assumes that the tectorial membrane is driven by a lymphatic fluid flow that can be shown to have a substantial radial component. It also assumes that the reticular lamina is relatively stiff and thereby restrains the top end of outer hair cells that exert a force to the basilar membrane via Deiters cells. When combined with a three-dimensional block model, it can simulate the sharp tuning mechanisms of the cochlea well.

Recursive formulae for the floating cone algorithm

ABSTRACT To the author's knowledge, the algorithm for establishing the sequential logic that defines the final limit of an open pit of maximum benefit remains to be developed. In a retrospective analysis on economic models and on optimization techniques applied to pit design, Kim (1979) recognizes the widely acceptance of the tri-dimensional block model and, in connection with it, of the heuristic method known as the floating cone. A recursive algorithm for building up floating cones of distinct shapes linked to the notion of norm (or distance) in a vectorial space is presented. Likewise, corresponding expressions for expanded floating cones are developed but, in contrast with the two-dimensional case, where all possible combinations of single floating cones can be generated, in the three-dimensional block model only unidirectional and isotropic expansions are considered. An hypothetical example illustrates results among three final pit designs generated on the same block model under different norm definitions

Limitations of the Cubical Block Model of Man in Calculating SAR Distributions (Comments)

The above paper raised some serious questions regarding the accuracy of three-dimensional block model solutions obtained using a pulse-function basis. While I am in qualitative agreement with about half of the numerical results presented in the paper, I most strongly disagree with most of the interpretations which the authors have made using those results. It is my belief that it is possible to obtain high accuracy with block model solutions if sufficient care is used in their implementation. I have chosen to use a pulse-function basis with block models of man since this appears to allow the model to have much greater detail than is possible with more elaborate bases.

Single unit activity in the posteroventral cochlear nucleus of the cat.

Single unit activity in the posteroventral cochlear nucleus (PVCN) was recorded for a variety of stimulus conditions. The units were classified according to their response characteristics. The locations of units were plotted onto a three-dimensional block model of the cochlear nucleus. Certain types of units that responded best to the onsets of stimuli were located predominantly in the octopus cell region of the PVCN. The remainder of the PVCN, which contains a rather heterogeneous collection of small and multipolar cells, was found to contain several types of units with the dominant type being "chopper" units.

A block model of the cat cochlear nucleus.

A three-dimensional block model of the cochlear nucleus of the cat was constructed from histologic sections. Boundaries of various subdivisions, based on cytoarchitectonic criteria, were included in the model. Usage of the block model in correlating physiological and anatomical data is illustrated by localizing characteristic waveforms of gross evoked responses and characteristic frequencies of single units.

Single unit activity in the dorsal cochlear nucleus of the cat.

Single unit activity was examined in three component layers of the dorsal cochlear nucleus (DCN): the molecular layer, the fusiform cell layer, and the polymorphic layer (deep DCN). Electrophysiological units were classified into types on the basis of their activity under a variety of stimulus conditions. In the molecular layer spike activity was small and difficult to isolate. Almost all units in the fusiform cell layer could be classified as either "pauser" or "buildup" units. Classification of units in the deep DCN was sometimes difficult, but "pauser," "chopper," and some "on" units were found. The "on" types of units tended to be located in the more superficial part of the deep DCN. Unit locations were referred to a three-dimensional block model of the cochlear nucleus.