Grade Mineral Research Articles

Industrial evaluation of a new flotation mechanism for large flotation cells

A new flotation mechanism was evaluated in the rougher flotation circuit at Collahuasi Concentrator Plant in Chile. For this purpose, the flotation mechanism FloatForce® was installed in one of three parallel rougher flotation lines, consisting of nine TankCell-160 (160m3) cells, while the other two lines operate with a conventional OK-mechanism. The evaluation was carried out based on a hydrodynamic and metallurgical characterization of the flotation circuits. Three overall samplings and mass balance adjustments for kinetic flotation characterization were performed. The residence time distribution RTD, of liquid and solids (per size class) was measured in the rougher lines using radioactive tracers. Thus, the effective mean residence time as well as the mixing condition in single flotation cells and along the rougher lines were evaluated. Also, measurements of axial solids segregation (per size class), axial mineral grade profiles, local superficial gas rate, bubble size distribution, bubble load and top of froth grades were performed in cells provided with both flotation mechanisms. The comparison of the rougher flotation operation with the FloatForce® and the conventional OK-mechanism is presented and discussed in this work.

Technology Study on Sichuan Refractory Lead-Zinc Ore

Rude ores, which were collected from two lead-zinc oxide ore deposits in Sichuan province, are very difficult to process with low grade and uneven mineral dissemination. It is very difficult to separate valuable minerals from gangue minerals, especially for the recovery of lead and zinc minerals. On the basis of mineral characteristic study, author studied flotation technology on lead-zinc mineral, and gained satisfactory concentrate indicator by stage-grinding: the lead concentrate with a grade of 52.45 percents and a recovery of 79.30 percents and the zinc concentrate with a grade of 35.26 percents and a recovery of 87.57 percents .

An investigation into the effect of water quality on froth stability

Froth stability plays a major role in determining the mineral grade and recovery in flotation operations, and it depends on the type and amount of both frother and suspended particles. Furthermore, there are other parameters such as quality of the process water which may affect the froth stability. In plant practice, the recycling of process water instead of using fresh water is increasingly being common. However, using recycled water normally leads to building up salts and surfactants in solution. Therefore, the effect of the process water chemistry on froth stability and metallurgical performance is important. In this study, the effect of water quality, including pH, and type and concentration of salts (CaCl2, AlCl3 and NaCl) on froth stability and its relationship with mineral particles zeta potential and slurry viscosity was studied. It was found that the forth stability is higher in the presence of multivalent metal ions. Addition of CaCl2 and AlCl3 considerably increased both froth stability and pulp viscosity. This may be due to bridging effect of polyvalent metal ions between the ore particles.

Application of fractal models to outline mineralized zones in the Zaghia iron ore deposit, Central Iran

Recognition of different mineralized zones in an ore deposit is important for mine planning. This study aims to separate the different mineralized zones and the wall rock in the Zaghia iron ore deposit situated in central Iran using the number–size (N–S) and concentration–volume (C–V) fractal methods. The N–S model reveals three geochemical zones defined by Fe thresholds of 24% and 40%, with zones <24% Fe representing weakly mineralized zones and wall rocks. The C–V model reveals four geochemical zones defined by Fe thresholds of 18%, 30% and 35%, with zones <18% Fe representing non-mineralized wall rocks. Both the N–S and C–V models indicate that high grade mineralization is situated in the northern part of the ore deposit. The results of validation of the fractal models with the geological model show that the N–S fractal model of highly mineralized zones is better than the C–V fractal model of highly mineralized zones. However, results obtained by means of the C–V fractal model for weakly and moderately mineralized zones are more accurate than the zones obtained by means of the N–S fractal model.

Condições físicas de formação de associações metamórficas do cinturão ultramáfico Carrancas-Liberdade, MG

Allochthonous ultramafic bodies occur associated with metasediments at Andrelândia Depositional Cycle in southern Minas Gerais. They cross regions belonging to the domains of the Brasília Belt and the interference tectonic zone between this and the Ribeira Belt. This paper discusses the differences in the metamorphic evolution of ultramafic rocks of both domains, based on equilibrium reactions, textural analysis and application of geothermometers. The high-grade rocks of a Ribeira Belt Tectonic Domain (meta-pyoxenites) show equilibrium conditions under higher temperatures (700 to 900°C) regarding to their congeners in the Brasília Belt Tectonic Domain (maximum of 640°C). Besides these contrasting temperatures the areas show different styles of deformation. In the Brasília Belt, the metamorphic peak is associated to pyroxene and olivine growth, followed by a deformation that affects the high grade rocks only in a discreet form. The main structures in this region are associated to a retro-metamorphic phase, represented by formation of hydrated rocks over the highest grade assemblages. In the domain of the Ribeira Belt, the formation of the highest grade minerals is concomitant to an intense deformation, indicating that the metamorphic peak coincides with the development of the dominant structures of ultramafic bodies.

Hydrothermal evolution of Daraloo porphyry copper deposit, Iran: evidence from fluid inclusions

The Daraloo field is located in the southeast of Iran (Kerman province). It is associated with Oligomiocene diorite/granodiorite to quartz monzonite stocks. Copper mineralization is basically relevant to potassic and phyllic alteration zones. Petrographic and geologic studies imply that mineralization is restricted to two major parts locating in the center and east of district. The larger central mineralization has a northwest–southeast trend perpendicular to the smaller one. Hydrothermal ore fluid formation occurred in relatively deep levels thereafter faulting and fracturing provided appropriate conduits to ascend fluids through shallower depths. Early hydrothermal alteration produced a confined potassic assemblage in the central and eastern parts of the stock. Two main fluid inclusion groups in relationship with alteration ore fluids have been identified. They are liquid-rich inclusions containing solid phases, with high temperatures (257°C to 554°C) and high salinities (31 to 67 wt.% NaCl equiv.), and vapor-rich inclusions with high temperatures and low salinities without any solid phases. These magmatic source fluids are responsible for boiling and also potassic and phyllic alteration zone. They also resulted in the formation of quartz groups I and II veins and chalcopyrite deposition. Propylitic alteration is attributed to a Ca-rich meteoric fluid. Inclusions originated from this fluid are liquid-rich having low temperatures (161°C to 269°C) and low salinities (1 to 13 wt.% NaCl). Mixing descending meteoric water with magmatic fluids reduces considerably the salinity of magmatic fluid. Mixing is also the impetus of leaching copper from potassic to the phyllic zone. It is possible to conclude that all these procedures are controlled by the main faults of district having NW–SE trend. Two fundamental events affecting the mineralization are cooling ore-bearing fluids and magnetite (±pyrite) emplacement. The latter one is formed in potassic and phyllic alteration zone in which copper-bearing fluids have interaction with magnetite minerals and so chalcopyrite minerals have been formed nearby magnetites. Temperature and pressure of hydrothermal fluid differentiation could be applied as a predictive tool to discriminate between barren and productive copper porphyry deposits. A simple comparison of temperature and pressure variations between Daraloo deposit and other copper porphyry deposits located in the same belt of Iran (Sahand-Bazman belt) illuminates that Daraloo system has high range of pressure implying deeper exsolution of hydrothermal fluid. On the other hand, economic mineralization has direct relationship with temperature range of orthomagmatic fluids so that if a deposit has a wide range of high temperature fluids, it could be inferred as a barren deposit. In conclusion, it could be inferred that Daraloo district can be categorized as a sub-economic porphyry deposit. On the other hand, restricted formation of chalcopyrite and the other copper-bearing minerals besides large amounts of magnetite and pyrite can approve obviously the low grade of mineralization in Daraloo district.

The Effects of Several Postharvest Treatments on Shelf Life Quality of Bunch Tomatoes

Bunch tomatoes (Lycopersicon lycopersicum L.) ‘Bandita’ cv. were hand-harvested at red ripe stage. The plants were grown on hanging carrying system with high wire support training in coco peat media in a plastic greenhouse located in Antalya (Turkey). Harvested fruits were divided to four groups for these treatments: (1) control-not treated; (2) tomato wax (Tomato wax is a wax formulated from 99% food grade mineral oil and 1% water); (3)Nutrient solution (1% potassium nitrate + 0.5% zinc sulfate + 1% calcium chloride + 0.1% boron + 0.2% copper sulfate + 0.5% ascorbic acid + 0.1% salicylic acid) and (4) Herbal oil (Herbal oil is a natural product obtained from hazelnut fruit membrane contains a high level of antioxidant). Bunches, placed in carton boxes, stored at 20°C temperature and 90±5% relative humidity for 16 days. Weight loss of bunches, firmness, respiration rate, ethylene production, colour, soluble solid content, pH, titratable acidity and sensory attributes (external appearance and taste-aroma of fruits and wilting and drying of calyxes) of tomatoes were evaluated during storage. Tomato wax treatment was limited the weight loss and preserved firmness better than the others. Tomato wax, nutrient solution and herbal oil treatments were limited the respiration rate. Ethylene production of nutrient solution treated fruits showed the highest value followed by herbal oil, tomato wax and control group. The highest colour change was found in control group. The lowest soluble solid content and the highest level of acidity were found in fruits treated with tomato wax. Control , herbal oil and nutrient solution treatments were lost marketable quality after 8 days of storage. TW treatment gave the best result and provided to store bunch tomatoes at good quality for 12 days.

Low grade uranium deposits of India – a bane or boon

Abstract Uranium resources of the world is estimated to be 5.5 million tonnes and the proven resources in India forms 3% of the world resources. The biggest uranium deposit is the Olympic dam deposit in Australia, which contains nearly 2.45 million tonnes of 0.023% U3O8, while the highest average grade of nearly 21% is established in the McArthur river deposit, Canada. Another very high grade deposit, the Cigar lake deposit, is also in Canada with an average grade of nearly 18%. Most of the uranium deposits established in India so far falls under the category of low grade. These low grade uranium deposits are distributed mainly in Singhbhum Shear Zone, Jharkhand; in parts of Chhattisgarh; Southern parts of Meghalaya; Cuddapah Basin, Andhra Pradesh; in parts of Karnataka and Aravalli- and Delhi Supergroups, Rajasthan and Haryana. These deposits are mainly hydrothermal vein type, stratabound type and unconformity related. The Singhbhum Shear Zone, Jharkhand hosts seventeen low grade vein type uranium deposits, aggregating about 30% of Indian uranium resources. The stratabound uranium mineralisation hosted by Vempalle dolostone extends over 160 km belt along southwestern margin of Cuddapah Basin in Andhra Pradesh and accounts 23% of the Indian resources. Though the dolostone hosted Tummalapalle uranium deposit was established in the early nineties, because of techno -economic constraints, the deposit remained dormant. As a consequence of the development of an innovative pre ssure alkali leaching process, the deposit became economically viable and a mine and mill are being constructed here. Recent exploration inputs are leading more such strata-bound low grade uranium deposits in the extension areas of Tummalapalle. Nearly 10 blocks have been identified within a 30 km belt which are being actively explored and a large uranium deposit has already been proved in this province. The deposit at Tummalapalle and adjoining areas is likely to emerge as one of the larger deposits in the world. The northern parts of Cuddapah basin in Andhra Pradesh is the host for unconformity related low grade uranium deposits. Four low grade low to medium tonnage deposits viz. Lambapur, Peddagattu, Chitrial and Koppunuru have been established in this province along the contact between basement granite and Proterozoic sedimentary rocks. This province also holds promise for large tonnage-high grade mineralization in the deeper unexplored parts of the basin. The North Delhi Fold Belt in the states of Rajas than and Haryana is the host for albitite/vein type uranium mineralization. A 320 km long NE-SW trending zone of deep seated fractures is the locus of mineralization and the mineralization is caused by soda metasomatism. A low grade uranium deposit is already established at Rohil associated with albitites and vast areas in this zone is open for exploration. The Cigar lake deposit, one of the two very high grade deposits in the world, though discovered in the year 1991 remains unexploited because of it high grade and requirement of remote handling and high end mining technology. The Mc Arthur deposit is being mined by raisebore mining method and the entire operation is carried out by 750 employees. Because of the high grade nature of the ore, it is diluted with barren rocks to bring the grade into manageable level before the beneficiation. The Rossing uranium deposit in Namibia, the biggest opencast mine for uranium, is of low grade and produces nearly 8% of the global output. As a result of the massive minin g and beneficiation operation, the employment of manpower is also very high compared to the high grade deposits. India, being a developing country with a high rate of unemployment, should treat the low grade deposits as an opportunity for employment. The operation of Rossing mine in Namibia is a shining example of as to how a low grade deposit could be economically exploited in the national interest and still be among the top five countries in terms of production. Inspite of mining the low grade resources, uranium mining industry in India provides direct and indirect employment to thousands of people and still operates in profit mode. Environmental concerns and radiation exposure to mining and milling personnel is negligible in the case of low grade deposits. The new mines, which are going to be opened in Tummalapalle, Andhra Pradesh; KPM (Domiasiat), Meghalaya; Gogi, Karnataka; Rohil, Rajasthan etc. will create substantial direct and indirect employment opportunities and transform the economy of these regions.

Plant communities of the ironstone ranges of South Western Australia: hotspots for plant diversity and mineral deposits

Plant communities of ancient banded iron formation ranges of South Western Australia occur as islands in a matrix of the largest remaining area of Mediterranean woodlands and shrub lands on the planet. These xeric shrub lands are structurally and compositionally different from the surrounding matrix and exhibit high levels of endemism and species turnover that cannot be ascribed to geology or current climatic gradients. The pattern of the vegetation and flora on these ranges appears to be related to local topographical factors and the long period of time these landscapes have remained unglaciated and above sea level. Similar patterns have recently been described for iron outcrop communities in Brazil. In both regions these communities are being significantly impacted by mining. The high correlation between local endemism and restricted plant communities and high grade mineral deposits presents difficult challenges for achieving a comprehensive, adequate and representative reserve system in South Western Australia.

Flotation of copper sulphides assisted by high intensity conditioning (HIC) and concentrate recirculation

This paper describes the effect of the partial concentrate (rougher floated product) recirculation to rougher flotation feed, here named concentrate recirculation flotation – CRF, at laboratory scale. The main parameters used to evaluate this alternative approach were flotation rate and recovery of fine (“F” 40–13 μm) and ultrafine (“UF” <13 μm) copper sulphide particles. Also, the comparative effect of high intensity conditioning (HIC), as a pre-flotation stage for the rougher flotation, was studied alone or combined with CRF. Results were evaluated through separation parameters, grade-recovery and flotation rates, especially in the fine and ultrafine fractions, a very old problem of processing by flotation. Results showed that the floated concentrate recirculation enhanced the metallurgical recovery, grade and rate flotation of copper sulphides. The best results were obtained with concentrate recirculation flotation combined with high intensity conditioning (CRF–HIC). The kinetics rate values doubled, the Cu recovery increased 17%, the Cu grade increased 3.6% and the flotation rates were 2.4 times faster. These were accompanied by improving 32% the “true” flotation values equivalent to 2.4 times lower the amount of entrained copper particles. These results were explained and proved to proceed by particle aggregation (among others) occurring after HIC, assisted by the recycled floatable particles. This “artificial” increase in valuable mineral grade (by the CR) resulted in higher collision probability between hydrophobic particles acting as “seeds” or “carrier”.

Comparison between Ozonation and Photo-Fenton Processes for Pesticide Methomyl Removal in Advanced Greenhouses

So-called “Advanced Greenhouses” are a new approach to the concept of protected agriculture. Among other technological and structural improvements, these facilities give the possibility of recycling the irrigation surplus water, rich in lixiviates, salts, pesticides and its metabolites. After many cycles, the current is so concentrated on those substances that it becomes necessary for the presence of a membrane separation stage which brine, highly concentrated on those named pollutants, has to be treated before being sent to the public sewage system. Advanced Oxidation Processes, among other chemical treatments, can be considered an alternative to process this current effluent. In this work, concentrated aqueous solutions of methomyl as model pesticide (200 mg·L−1) have been subjected to two of those processes: ozonation and photo-Fenton reaction. Analysis of the elimination of the pesticide itself and the grade of mineralization achieved have shown how, while the ozonation is the most effective process decomposing the pesticide (eliminating the total concentration in 60 minutes), the photo-Fenton reaction mineralizes successfully the 40% of the total organic load (the ozonation only can cope with 20%) but only decompose a 40% of the pesticide. Evolution of biodegradability and toxicity of the effluent along both processes was also analyzed. Intermediates generated both by ozonation and photo-Fenton did not increase the biodegradability of the treated effluents. Nevertheless, while acute toxicity just after 15 minutes of treatment with ozone is notably higher than for raw solution, and it is maintained till the end of the experiment (120 min), though, toxicity along photo-Fenton reaction has two growing and decreasing regions, always shows lower values than the provoked during ozonation. None of the two assayed processes has been proved to increase biocompatibility of highly concentrated methomyl solutions.

Evaluation of a new oil adjuvant for use in peptide‐based cancer vaccination

Vaccine therapies are increasingly being used for the treatment of various diseases, and the antigen molecules themselves are being expanded from whole microorganisms to fine molecules such as peptides. Accordingly, there is a need for new adjuvants to support these new applications. In this paper, we used pharmaceutical grade mineral oil and sorbitan monooleate to develop a new oil adjuvant formula, NH(2) , and investigated its effects on peptide vaccination at both the pre-clinical and clinical levels. The adjuvant effect of NH(2) on peptide-induced cellular immunity in mice was superior to that of Montanide ISA51VG, a commercially available incomplete Freund's adjuvant for clinical use, although no significant difference was observed between the two adjuvants on peptide-induced humoral immunity. The adjuvant effects of NH(2) were also confirmed in a Phase-I clinical trial of peptide vaccines for patients with advanced cancers. These results suggest that NH(2) is a suitable adjuvant for peptide vaccination, particularly for cancer vaccines (Phase-I clinical trial of pan-HLA type personalized peptide vaccine for advanced cancer patients, UMIN clinical trial registry number: UMIN 000000619).

Application of 3D geochemistry to mineral exploration

ABSTRACT The development of sophisticated 3D visualization software has made it possible to fully integrate geological, geochemical, and geophysical data in three dimensional space creating new opportunities to explore data relationships. The advent of inexpensive, multi-element ICP-MS (inductively coupled plasma-mass spectrometry) analysis techniques with low detection limits has led to the identification of zoned element associations and their spatial relations to ore with great efficiency and clarity. Geochemical modelling of down-hole data has advantages in pattern recognition by facilitating the creation of 3D volumes. This is achieved by producing individual element block models using a gridding algorithm to interpolate concentrations between drill-holes. The block models provide an effective means of exploring relationships in the down-hole data and integrating this information with other subsurface data (geological lithology logs, geophysical inversions) and surface data (geochemistry, geology and geophysics). A key prerequisite for geochemical modelling is the acquisition of down-hole data distributed in a generally systematic fashion along each hole. Some inconsistencies in a geochemical database that need to be addressed prior to modelling include: (1) relative accuracy shifts over time in data reported from a single laboratory or between different laboratories; (2) variable detection limits amongst datasets; (3) mixed partial and total extraction data; (4) special values or zeros representing data below detection limit or missing data; and (5) mixed reporting units. Some applications of 3D geochemistry include: (1) stratigraphic correlation using elements not introduced or significantly redistributed during the mineralizing event; (2) development of a conceptual zonation model of a mineral system; (3) identification of vector criteria for locating high grade mineralization based on zonation relationships; (4) distinguishing proximal from distal signatures; (5) improving vectoring by integrating surface and sub-surface data; (6) improving interpretation of surface data by understanding the effects of surface weathering; (7) locating the bedrock source of anomalies in 3D overburden data; and (8) increasing the understanding of mineral systems and dispersion phenomena. Most of these applications are illustrated using a schematic zonation model for Carlin-type sediment-hosted gold systems in Nevada, USA, a 3D model of the Sleeper low sulphidation gold system in Nevada, and a 3D model of mobile ion dispersion in glacial overburden over the Shoot gold zone, Ontario, Canada.

Emerging mitigation needs and sustainable options for solving the arsenic problems of rural and isolated urban areas in Latin America – A critical analysis

In this work, current information about the contamination of ground- and surface-water resources by arsenic from geogenic sources in Latin America is presented together with possible emerging mitigation solutions. The problem is of the same order of magnitude as other world regions, such as SE Asia, but it is often not described in English. Despite the studies undertaken by numerous local researchers, and the identification of proven treatment methods for the specific water conditions encountered, no technologies have been commercialized due to a current lack of funding and technical assistance. Emerging, low-cost technologies to mitigate the problem of arsenic in drinking water resources that are suitable for rural and urban areas lacking centralized water supplies have been evaluated. The technologies generally use simple and low-cost equipment that can easily be handled and maintained by the local population. Experiences comprise (i) coagulation/filtration with iron and aluminum salts, scaled-down for small community- and household-scale-applications, (ii) adsorption techniques using low-cost arsenic sorbents, such as geological materials (clays, laterites, soils, limestones), natural organic-based sorbents (natural biomass), and synthetic materials. TiO 2-heterogeneous photocatalysis and zerovalent iron, especially using nanoscale particles, appear to be promising emergent technologies. Another promising innovative method for rural communities is the use of constructed wetlands using native perennial plants for arsenic rhizofiltration. Small-scale simple reverse osmosis equipment (which can be powered by wind or solar energy) that is suitable for small communities can also be utilized. The individual benefits of the different methods have been evaluated in terms of (i) size of the treatment device, (ii) arsenic concentration and distribution of species, chemical composition and grade of mineralization in the raw water, (iii) guidelines for the remaining As concentration, (iv) economical constrains, (v) complexity of installation and maintenance, and infrastructure constraints (e.g. electricity needs).

Is recycled newspaper suitable for food contact materials? Technical grade mineral oils from printing inks

Recycled paper and board used in food packaging materials (boxes, paper bags) often cause migration of mineral oil into food at levels which are unacceptable according to present toxicological assessments. When foods in recycled board are densely packed into larger boxes or onto pallets, most of the hydrocarbons up to n-C20 may migrate into the packed food within a few weeks, those up to n-C28 at a decreasing rate. Unprinted recycled board contained 300–1,000 mg/kg mineral oil <n-C28. The main sources are the inks used for printing newspapers: newspapers contained roughly 3,000 mg/kg mineral oil <n-C28. These mineral oils fall into classes for which JECFA established a tolerable daily intake of 0.01 mg/kg body weight. Using standard assumptions for calculating specific migration limits, a maximum tolerable concentration in food of 0.6 mg/kg is derived. This evaluation assumes highly refined white oils, whereas the oils found in recycled board are of technical quality and contain 15–25% aromatic compounds, predominantly with 1–3 aromatic rings, as shown by comprehensive GC × GC. This finding precipitates authorities into a dilemma: recycling is supported for the sustainable use of materials, but on the basis of present toxicological assessments the migration is often far beyond acceptable.

Porphyry Copper Systems

Porphyry Copper Systems

菱刈鉱山におけるＳｕｂｌｅｖｅｌ Ｏｐｅｎ Ｓｔｏｐｉｎｇ（ＳＬＯＳ）導入に関する研究

The Hishikari Mine is the only major gold mine operating in Japan, whose production rate in 2008 was around 184,000 tonnes with the average gold grade of 42.8 g/t. The gold veins are extracted mainly by drifting and bench stoping with backfill. Blasted waste rocks are generally used as backfill materials and crushed waste rocks with cement (cemented rock fill) are used for larger stopes. In order to extract the KE-2 vein with wider mineralization and lower grade, being closely located to the narrower KE-3 vein with higher gold grade, we have studied the applicability of the sublevel open stoping (SLOS) with cemented rock fill through in-situ measurements of rock mass displacements and numerical stress analyses for evaluating the stability of the KE-2 large SLOS stopes and interaction with the KE-3 bench stopes.We have used a bi-linear stress-strain characteristics of backfill for modeling the nonlinear compaction of cemented rock fill, whose stiffness increases with wall displacements of the backfilled stopes. The non-linear compaction may affect support characteristics of backfill, the present paper, therefore, incorporates the two-stage/bi-linear compaction modeling of backfill in FLAC3D in order to analyze the supporting effects of the cemented rock fill and to investigate the required backfill quality and mining sequence for more stable and steady operations of the KE-2 and KE-3 stopes.

Application of highlight removal and multivariate image analysis to color measurement of flotation bubble images

AbstractMachine vision based analysis provides a novel technology for froth flotation monitoring. Froth images collected are characterized by fully occupied bubbles with different size and shape under various illuminations. Convex bubbles lead to the formation of white spots that seriously affect froth color measurement. In this article, specular highlights are detected and preprocessed so as to estimate underlying color of white spots region. Because of the fact that color information is believed to be related to flotation performance, therefore, after the application of highlight inpainting, multivariate image analysis is proposed to extract color features, which are further related to mineral grades by a orthogonal least square regression model. The established relationship provides a promising empirical model to predict mineral grade, which is a significant indicator for flotation performance. Experimental results show that, when compared with traditional methods, the proposed algorithm can achieve a robust color measurement and predict mineral concentration effectively. © 2009 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 19, 316–322, 2009

Change-of-support models and computer programs for direct block-support simulation

This article presents a computer program to directly simulate continuous regionalized variables such as mineral grades over a block support. Simulation is performed in the scope of the discrete Gaussian model and does not rely on a block discretization. The realizations can be made conditional to point-support data by use of simple or ordinary kriging, depending on whether or not the average value of the data is considered known. The proposed program can account for an information effect (misclassifications between ore and waste) by co-simulating the true block-support grades together with the grades that will be predicted at the production stage to discriminate between ore and waste.

Influence of Structural Principles on the Mechanics of a Biological Fiber‐Based Composite Material with Hierarchical Organization: The Exoskeleton of the Lobster Homarus americanus

AbstractThe cuticle of the lobster Homarus americanus is a nanocomposite, such as most structural biological materials. It consists of a matrix of chitin‐protein fibers associated with various amounts of crystalline and amorphous calcium carbonate in the rigid parts of the body, and is organized hierarchically at all length scales. One prominent design principle found in the hierarchical structure of such biological fibrous composite materials is the twisted plywood structure. In the lobster cuticle, it is formed by superimposing and gradually rotating planes of parallel aligned chitin‐protein fibers. To adjust the mechanical properties to the requirements on the macroscopic level, the spatial arrangement and the grade of mineralization of the fibers can be modified. A second design principle of lobster cuticle is its honeycomb‐like structure, generated by the well‐developed pore canal system, whose twisted ribbon‐shaped canals penetrate the cuticle perpendicular to its surface. Due to the hierarchical structure, the mechanical properties of the lobster cuticle have to be investigated at different length scales, which is essential for the understanding of the structure–mechanical function relations of mineralized tissues (e.g., potentially also bone and teeth). In order to investigate the influence of the structural principles on the mechanical properties on the macroscopic scale miniaturized tensile, compression, and shear tests were carried out to obtain integral mechanical data. Characterization of the microstructure included scanning electron microscopy (SEM) combined with energy dispersive X‐ray (EDX) measurements.