Ore Block Research Articles

Research and Practice of Rock Mechanics for Mining of Large and Thick Pillars with Inclusion of Fillings

Through investigation and test analysis of current situation of testing stope and surrounding filling and isolation layer of mines, understand the basic mechanical characteristics and integrity characteristic of surrounding rock mass and fillings of chamber to be mined; combining with comparative analysis of technical and economic index of mining, considering making full use of the existing personnel, equipment and technology, it is concluded that stoping technology scheme of chamber is large-diameter deep-hole afterwards filling mining method; by using the numerical analysis method, through comprehensive analysis of stress, deformation and failure characteristics of surrounding fillings in mining, finally determine the optimal recovery scheme is mining by recovery unit of upper and lower plate. At present the ore block has been successfully and safely mined. Research results can provide reference for recovery of similar ore block, in order to realize safe and efficient recovery of "island" ore block in mining with filling mining method.

Spectrophotometric characterization of iron and titanium minerals in sedimentary kaolin deposit

The northern region of Brazil produces kaolin for paper industry. Ipixuna Mine, located in the Pará State, exploits important sedimentary kaolin deposits, which are extracted ROM material blocks that vary in color depending on both the paragenesis and concentration of mineral contaminants. Samples were collected from different mining fronts, which represented the different varieties of ore. Samples were processed in a pilot plant. Both products and tailings were analyzed to define the mineral paragenesis and color data. Specific studies on the iron and titanium minerals and spectrophotometry were performed on the samples. The results indicated that the proportion of goethite, hematite and anatase and the particle size of the last two minerals in the blocks of ore affect their color and mineral processing efficiency. This study defined seven spectral groups of kaolin ore, the relationship of the groups with the paragenesis of mineral contaminants, varieties of ore that can be economically processed and the best blending options between ore varieties to improve the processing operations.

Deposit Digitizing for JiaYaShan Ore Block in LanPing Pb-Zn Mine

Lanping Pb-Zn mine is the biggest Pb-Zn mine of China. It is necessary for the mine to digital. On the basis of systematic analysis of and research on Jiayashan ore block in Lanping pb-zn mine, Mine Mathematical Model software, Surpac software and Micrmine software from abroad for digitization ware used to study this deposit. Finally, a three-dimensional space deposit model was established. As a result, the dynamic management of mine has been realized, the degree of automation and systematize have been increased for mining production, the scientific help have been presented for making use of resources sufficiently and reasonably.

Development of ‘radial-in-reef’ stoping at Tasmania Gold Mine, Beaconsfield, Tasmania

An alternative stoping method has been adopted for narrow vein stoping at the Tasmania Mine in Northern Tasmania. Colloquially described as ‘radial-in-reef’ stoping, the method employs the drilling of radial rings in the plane of the Reef from a drill stub located at the geographic centre of the proposed stope panel. Production from the western zone of the Tasmania Reef has been undertaken remotely from the Reef since 2007 after a detailed geotechnical engineering analysis indicated that the integrity of the sill drives could not guarantee an acceptable level of confidence should an anticipated seismic event occur within a radius of 10 m. The key tenet of the remote mining approach was the exclusion of personnel from sill drives once stoping had commenced. The remote mining method had to be ‘retrofitted’ to four existing stoping blocks totalling 11 sill drives which totalled 160 m vertically. The remote mining method proved to be complex, cumbersome and very expensive. However, the ore was extracted successfully. By early 2010, previously developed ore had largely been exhausted and the future development with an orebody open at depth presented the opportunity to review the current extraction method. However, the new extraction method needed to maintain the tenet of excluding personnel from sill drives of active stoping blocks, but seek opportunities to reduce the difficult and costly aspects of the previous method. The new ‘radial-in-reef’ stoping reduced the development requirement from six to two drives per ore block. Cost implications aside, the significant reduction in prestoping extraction ratio was expected to also reduce the likelihood of seismicity. Transverse production rings were designed to be drilled radially from a drill stub mined from a midstope footwall drive. Stopes totalling up to 7000 t were planned to be fired in a single electronic blast. Extraction was designed to take place from a basal sill drive under teleremote operation. At the time of writing, the method was under trial.

Circle geometric constraint model for open-pit mine ore-matching and its applications

The circle geometric constraint model (CGCM) was put forward for resolving the open-pit mine ore-matching problems (OMOMP). By adopting the approaches of graph theory, block model of blasted piles was abstracted into a set of nodes and directed edges, which were connected together with other nodes in the range of circle constraints, to describe the mining sequence. Also, the constructing method of CGCM was introduced in detail. The algorithm of CGCM has been realized in the DIMINE system, and applied to a short-term (5 d) program calculation for ore-matching of a cement limestone mine in Hebei Province, China. The applications show that CGCM can well describe the mining sequence of ore blocks and its mining geometric constraints in the process of mining blasted piles. This model, which is applicable for resolving OMOMP under complicated geometric constraints with accurate results, provides effective ways to solve the problems of open-pit ore-matching.

3D Positional and Quantitative Prediction of the Xiaoqinling Gold Ore Belt in Tongguan, Shaanxi, China

Abstract:Quantitative prediction of deep orebody based on 3D visualization technology is of great significance in mineral exploration. Based on the 2D traditional quantitative predicting method, the geoanomaly theory and the mineral exploration model idea, we constructed 3D models of the topography, strata, structure, magmatite and prospecting engineering of the study area using the commercial 3D modeling software Micromine, delineated eight prospective areas and estimated the gold resources amount with methods of Abundance Estimation and Volume Estimation. Then, we compared and counted the known ore blocks and the predicted blocks, which quantitatively explains this prediction's validity. The results show that Xiaoqinling gold belt in Tongguan has convincing potential for gold development and utilization and the prediction method based on 3D visualization technology proves to be effective.

Sampling and analysis of chemical element concentration distribution in rock units and orebodies

Abstract. Existing sampling techniques applied within known orebodies, such as sampling along mining drifts, yield element concentration values for larger blocks of ore if they are extended into their surroundings. The resulting average concentration values have relatively small "extension variance". These techniques can be used for multifractal modeling as well as ore reserve estimation approaches. Geometric probability theory can aid in local spatial covariance modeling. It provides information about increase of variability of element concentration over short distances exceeding microscopic scale. In general, the local clustering of ore crystals results in small-scale variability known as the "nugget effect". Parameters to characterize spatial covariance estimated from ore samples subjected to chemical analysis for ore reserve estimation may not be valid at local scale because of the nugget effect. The novel method of local singularity mapping applied within orebodies provides new insights into the nature of the nugget effect. Within the Pulacayo orebody, Bolivia, local singularity for zinc is linearly related with logarithmically transformed concentration value. If there is a nugget effect, moving averages resulting from covariance models or estimated by other methods that have a smoothing effect, such as kriging, can be improved by incorporating local singularities indicating local element enrichment or depletion. Although there have been many successful applications of the multifractal binomial/p model, its application within the Pulacayo orebody results in inconsistencies, indicating some shortcomings of this relatively simple approach. Local singularity analysis and universal multifractal modeling are two promising new approaches to improve upon results obtained by commonly used geostatistical techniques and use of the binomial/p model. All methods in this paper are illustrated using a single example (118 Pulacayo zinc values), and several techniques are applied to other orebody datasets (Whalesback copper deposit, Witwatersrand goldfields and Black Cargo titanium deposit). Additionally, it is discussed that nugget effects exist in a binary series of alternating mostly gneiss and metabasite previously derived from KTB borehole velocity and lithology logs, and within a series of 2796 copper concentration values from this same drill-hole.

Three-Dimensional Model of Cangshang Gold Mine Based on Surpac

The three-dimensional geological model of Cangshang Gold Mine, including the geological database, ore body model and block model, was established by mining software Surpac, which simplified the complicated hand-drawing and reserve calculation. The three-Dimensional development system visualization was also studied on the basis of conducting the vectorization of the whole development system design including excavation and construction project. The establishment of mine three-dimensional geological model simplified the complicated hand-drawing and reserve calculation. The calculation results are accurate, which can be used in the resource estimation, reserve calculation and mine design of the mine production stage.

The Application of Ore Surface Model in Computer State Delineating Method

Traditionally, the computer method of delineation requires to establish ore block model. The block-by-section scanning operation is slow, which does not meet the large amount of data calculation., In this paper, we use the ore body in the modeling of the surface model in order to overcome the above problem. This model uses modeling method that reproduces a traditional hand-paintedtechnique, describe the spatial distribution of ore bodies through a series of plan view or profile of the ore body boundary polygon for wireframe modeling, i.e., the frame modeling method. For reading the plan view or profile of the ore body, the graphics and fractal theory are needed in the work to achieve the extraction of vector graphics map elements. After completing the extraction of ore, the wireframe modeling of the ore bodies can be established by using wireframe modeling method. Finally the wireframe model is filled by using the OpenGL technology and the surface model orebody is generated.

Influence of the ore block model estimation on the determination of the mining cutoff grade policy for sustainable mine production

Strategic mine planning includes different cut-off grade policy depending on economic parameters of mining projects and grade–tonnage distribution of the deposit. Minimizing incorrect classification of ore and waste during grade–tonnage distribution is of critical importance for a mining operation. This article reviews the influence of the ore grade–tonnage distribution over the cut-off grade policy in a given mining operation. In this study, firstly, the interpolation parameters used to characterize the grade–tonnage distribution in the orebody are given. The resulting distribution of ore and waste is used to analyze uncertainty, risk impact, and to justify mine-planning decisions, according to the interpolation technique used and the number of geological settings and sampling scenarios being considered. Then, the working scheme of the cut-off grade policy and economic parameters are compared according to the resulting estimation from the inverse distance and the nearest neighbor methods.

3D visualisation of portable X-ray fluorescence data to improve geological understanding and predict metallurgical performance at Plutonic Gold Mine, Western Australia

The amphibolite-facies metabasaltic rocks of the Mine Mafic Package at Plutonic Gold Mine, Western Australia, contain an estimated endowment of 10·5 Moz of Au. A preliminary study based on portable X-ray fluorescence (pXRF) analyses identified a geochemical stratigraphy which strongly controlled the location of Au mineralisation. The present study incorporates a significantly larger pXRF dataset and presents the data in a three-dimensional framework. This dataset allows an investigation of the mineralogy of Au mineralisation with varying geochemical associations across the deposit. Historically, high As content in the mill feed resulted in poor metallurgical performance. Seamless data integration of the pXRF dataset allows for recognition of the different styles of Au mineralisation based on Au/As ratios, and visualisation of the distribution of these different mineralogical associations in three dimensions. This work enables us to better predict the As concentration of underground ore blocks, and to be proactive in optimising the mill configuration to improve metallurgical performance.

A mine planning model to satisfy long-term grade targets

This paper describes a technique to predict the head grades and likely variances from target grade that can be achieved from mining an iron ore deposit. The method develops a production schedule from a block model. The example used was created from a wide-spaced drilling program and was classified as an Inferred Resource, but the method can be applied to any block model based on the available combination of Proved and Probable reserves. Marketing contracts require examination whether the target grade, i.e. Fe, P, SiO2, Al2O3, can be kept constant, or must be revised during the life of the mine. A model (written in Excel using Visual Basic macros, details available from the first author) develops a feasible, close to optimal, mine plan from block model data. Cut-off grades for minable ore are chosen. The model evaluates ore tonnage, grade and stripping ratio against depth. Outputs at this stage include plots of slices through the ore body, at nominated x, y and z coordinates, showing ore grade, waste, drill-hole locations and topography. The model then searches for a feasible satisfactory mine plan. The initial grade target is the average for the identified ore blocks. The available block list (ABL) at any time is the set of ore blocks, any one of which can be mined without removing any other ore block. The entire initial ABL has an unacceptably large total stress, defined as [(Grade–Target)/Tolerance]2, summed over the four relevant minerals. The model trims the ABL, removing the block most harming the total stress. Trimming is repeated until the Total Stress reduces to an acceptable level. The trimmed ABL defines the first mine campaign. Removing the trimmed block set, a second ABL is exposed, which is again trimmed and mined. The process is automatic: a few seconds computation provides a complete mine plan. Re-running the model with adjusted grade limits quickly shows whether a uniform target can be achieved or whether the target must be modified during the mine life.

Optimisation of the grade control procedures at the Yandi iron-ore mine, Western Australia: geostatistical approach

Effectiveness of ore grade control at operating mines depends on both the quality and quantity of the samples used. Therefore, optimisation of grade control procedures requires analysis of sample quality and their spatial distribution. This approach, implying quantitative estimation of both these factors and quantification of their contribution to the grade control errors, was used for comparing two different grade control procedures at the Yandicoogina (Yandi) iron-ore open pit mine, located in the eastern part of the Pilbara region of Western Australia. At Yandi, pisolitic iron oxide mineralisation is distributed within a meandering palaeoriver channel, characterised by abundant clay pods that contain the deleterious components; in particular Al2O3 and SiO2. The irregular shapes and highly erratic distribution of the clay pods are a serious challenge for grade control at this mine. Current grade control procedures at the Yandi open pit are based on sampling 10 m deep blast holes on a 6 × 6 m grid. An alternative approach was considered of using reverse circulation (RC) holes. However, study of the sample duplicates and direct comparison of the blast holes and RC holes drilled at distances approximately 1 m apart (i.e. twin holes) have revealed that use of RC drilling does not guarantee an improvement in the quality of the samples. Reverse circulation samples exhibit precision errors similar to that of the blast holes and both sets of data are characterised by large nugget effects on the variograms of Al2O3 values. It was also noted that RC samples were biased, underestimating Al2O3 and SiO2 grades, and overestimating Fe grades. The Sequential Gaussian conditional simulation model was used for estimation of grade control errors associated with both grade control techniques. This model has shown that using a grid of 25 × 25 m for grade control leads to 12·3% of the selective mining unit sized blocks being misclassified, which is more than a two-fold increase in comparison with current procedures based on sampling blast holes, when approximately 5·8% of SMU blocks are misclassified. In general, comparative analysis of the two grade control approaches at the Yandi mine shows that using the RC holes drilled as the 25 × 25 m grid will not reduce the grade control errors. In fact, it can produce the opposite effect, significantly increasing the number of misclassified ore and waste blocks.

Bainiuchang super-large silver-polymetallic ore deposit related to granitic magmatism in Mengzi, Yunnan

Bainiuchang silver-polymetallic ore deposit is located in the southeast Yunnan tin-polymetallic metallogenic belt. The probable reserves and inferred resources of the deposit are of 6 470 t Ag and 1.10 Mt Pb and 1.72 Mt Zn and 86 kt Sn. Orebodies of the deposit occur in clastic-carbonate rocks of Tianpeng Formation and Longha Formation of the middle Cambrian System above the Bainiuchang concealed granite of the late Yanshan period. The concealed granite has the characteristics of tin-bearing granites. Abundance of the mineralization elements Sn, Cu, Zn, Pb, Ag and Sb is high in the granitic rocks. Sulphur isotope data of the metal sulphides indicate that most sulphur is derived from the magmas. The ores are similar in rare earth element(REE) patterns to the granitic rocks. The granitic magma activity results in ore-bearing structures. Rocks of the Middle Cambrian System above the concealed intrusion suffer from skarnization, hornfelsing, marbleization, siliconizing and carbonatization. The mineralization elements Sn, Cu, Zn, Pb, Ag and Sb successively appear from the top of the granite to surrounding rocks. These evidences indicate that the granitic magmatism is the principal mineralization factor. The opinion that the south Bainiuchang ore field and the north Awei ore block are tin and copper potential exploration areas was put forward and was verified by drilling tests.

Using chance constrained binary integer programming in optimising long term production scheduling for open pit mine design

The present paper attempts to model long term production scheduling problems by chance constrained binary integer programming in a stochastic environment. This stochastic model is set up to account for ore block grade uncertainty. The probability distribution function of grade in each block is used as a stochastic input to the optimisation model. This distribution function in each block should be determined using geostatistical simulation approach. The deterministic equivalent of proposed chance constrained model is then achieved which is the form of non-linear quadratic in binary variables. A confidence level at which it is desire that the uncertain constraints holds, is specified in each scheduling period. Rather than previous risk based model, this formulation will yield schedules with high chance of achieving planned production targets while maximises the expectation of net present value and minimises the variance function simultaneously. Using this method the grade uncertainty is integrated explicitly into the optimisation process.

The Falémé deposits, Republic of Senegal – an old kid, new on the iron ore block

The Falémé iron ore deposits are located in the so-called 'Birrimian' volcano-sedimentary complex that extends in a general NE-SW direction across Eastern Senegal and part of Mali and Guinea. The rocks underwent folding and greenschist facies metamorphism, as well as various events of granitoid emplacement. The deposits formed part of the Dialé-Daléma Series of the Birrimian Supergroup and were subjected to contact metamorphism. The Fe-mineralisation occurs as primary magnetite within the metamorphic aureole. Supergene oxidation (martitisation) of this mineralisation produced the hematite-rich iron deposits that can be seen as prominent hills across the plains of this southeastern corner of Senegal. The Bureau de Recherches Géologiques et Minières of France and Société des Mines de Fer du Sénégal Oriental have conducted several phases of prospecting since 1957. Their aim was to delineate the primary magnetite and oxidised ore (hematite) deposits and to assess the grade, beneficiation characteristics and marketability of the iron ore. A hematite feasibility study by Fluor Daniel was completed in 1992. Results indicated that, at the time, the resource could not compete in the international arena in terms of size and accessibility. The growing iron ore market and additional available resources in the area now challenge the 1992 feasibility study results and put the old kid back on the iron ore block. The project faces some mining challenges, such as the amount of magnetite in the hematite product that will be acceptable to the market. Previous project evaluations only considered the secondary hematite deposits as economically viable. It is therefore important to accurately delineate the magnetite/hematite contact zone to optimise the resource tonnage. Project logistic constraints also exist in terms of railway access and harbour facilities. The resource is, however, well situated for the European iron ore market and aims to find a place in the rapidly expanding iron ore seaborne trade.

Surface gravity vectors: an approach for open pit mine optimisation

Extraction sequence optimisation is highly complex with thousands of ore and waste blocks to be sequenced with respect to the net present value criterion. The aim of this study is to explain the surface gravity vectors approach, which is proposed to be used in open pit mine optimisation process. This approach uses an analogy between the universal gravity law and open pit mining. The economic values of the ore blocks are assumed as their mass and the extraction sequence is determined by the total gravity vector between the shovels and ore blocks.

Geomechanical Substantiation of Ore-Block Breaking Schemes Taking into Account Static Stress Field Redistribution under the Short-Delay Blasting

The features of the static stress field redistribution in a rock mass are established for schemes of blasting that form a sinusoid-shaped ore block without a free surface on the contact with caving zone. The influence exerted by caved rocks on the dimensions and location of tension zones in a broken block is estimated.

Two experimental iron smeltings (Congo and Rwanda)

During a prospection tour in northern Congo, in search for a site possibly solving the problem of the so-called “Neolithic” Uelian industry, interest was roused by the abundant haematite on the surface. This mineral had been used to produce the polished artefacts of the Uelian. Blacksmiths told us that these blocks of iron ore were formerly used to make iron. They were ready to show us and were very successful in doing so. Two other smelts were organized in Rwanda; they were unsuccessful, due to a loss of knowledge.

Geomechanical Substantiation of Borehole Charge Parameters in Breaking of Stressed Rock Mass

Using the mathematical modeling, the features of mechanical state of ore block are established with due regard for the action of explosive charges in the prestressed medium. The recommendations on the effective pattern of boreholes and optimal decrease in mass of charges are made.