Use of high-resolution X-ray computed tomography and 3D image analysis to quantify mineral dissemination and pore space in oxide copper ore particles

Mineral dissemination and pore space distribution in ore particles are important features that influence heap leaching performance. To quantify the mineral dissemination and pore space distribution of an ore particle, a cylindrical copper oxide ore sample (I center dot 4.6 mm x 5.6 mm) was scanned using high-resolution X-ray computed tomography (HRXCT), a nondestructive imaging technology, at a spatial resolution of 4.85 mu m. Combined with three-dimensional (3D) image analysis techniques, the main mineral phases and pore space were segmented and the volume fraction of each phase was calculated. In addition, the mass fraction of each mineral phase was estimated and the result was validated with that obtained using traditional techniques. Furthermore, the pore phase features, including the pore size distribution, pore surface area, pore fractal dimension, pore centerline, and the pore connectivity, were investigated quantitatively. The pore space analysis results indicate that the pore size distribution closely fits a log-normal distribution and that the pore space morphology is complicated, with a large surface area and low connectivity. This study demonstrates that the combination of HRXCT and 3D image analysis is an effective tool for acquiring 3D mineralogical and pore structural data.

3D characterization and analysis of pore structure of packed ore particle beds based on computed tomography images

Methods and procedures of three-dimensional （3D） characterization of the pore structure features in the packed ore particle bed are focused. X-ray computed tomography was applied to deriving the cross-sectional images of specimens with single particle size of 1-2, 2-3, 3-4, 4-5, 5-6, 6-7, 7-8, 8-9, 9-10 ram. Based on the in-house developed 3D image analysis programs using Matlab, the volume porosity, pore size distribution and degree of connectivity were calculated and analyzed in detail. The results indicate that the volume porosity, the mean diameter of pores and the effective pore size （d50） increase with the increasing of particle size. Lognormal distribution or Gauss distribution is mostly suitable to model the pore size distribution. The degree of connectivity investigated on the basis of cluster-labeling algorithm also increases with increasing the particle size approximately.

Economic Evaluation of Conventional Radiography with Film and Computed Radiography: Applied at BMC

Conventional radiography with film (CRF) has been in use for diagnostic purposes for a long time now. It has proved to be a great assert for the radiographers in assessing various abnormalities. With recent advances in technology it is now possible to have digital solutions for radiography problems at a very cost effective, environment friendly and also with better image quality in certain applications when compared to CRF. Rather than using a CRF a computed radiography (CR) uses imaging plates to capture the image. The imaging plate contains photosensitive phosphors which contain the latent image. Later this plate is introduced into a reader which is then converted into a digital image. The major advantage and the cost effective element of this system is the ability to reuse the imaging plates unlike the photographic film where in only a single image can be captured and cannot be reused. The computed radiography drastically reduces the cost by eliminating the use of chemicals like film developers and fixers and also the need for a storage room. It also helps to reduce the costs that are involved in the disposal of wastes due to conventional radiography. This paper investigates whether it is cost effective to use computed radiography over film based system at Al-Batnan Medical Center (BMC), Tobruk, Libya by using Cost Benefit Analysis (CBA). Apart from the initial cost of the CR System, based on the data collected from the center, from the year 2008 to 2012 (until June 2012) a total of 581,566 images were produced with the total cost incurred using film based system being USD 4,652,528. If the same number of images were produced using a CR system the total cost incurred would have been USD 82,600. Taking into consideration the cost of a new CR system to be USD 120,000 the overall cost of producing these images is USD 202,600. It is observed that an amount of USD 4,449,928 could have been saved over the period of 5 years starting from 2008 to 2012 by using the CR system at BMC. Using Cost Benefit Analysis, the average value of the net difference between the costs and benefits for the conventional film based system is ?83.38 where as for the Computed System it is 22.06. Based on the principles of Cost Benefit Analysis it can be concluded that the system with a net positive difference is more cost beneficial than the other. With the help of the above two analysis it can be concluded that the use of computed radiography is definitely more cost effective for use at BMC, when compared to the conventional x-ray radiography.

Effects of Using Municipal Solid Waste Incineration Tailings as Lightweight Aggregate on the Mechanical Properties of Specified Density Concrete

Municipal solid waste incineration tailings were used as lightweight aggregate(MSWIT-LA)in the preparation of specified density concrete to study the effects on compressive strength,axial compressive strength,flexural strength,microhardness,total number of pores,pore area,and pore spacing.The results showed that the internal curing and morphological effects induced by an appropriate quantity of MSWIT-LA improved the compressive response of specified density concrete specimens,whereas an excessive quantity of MSWIT-LA significantly reduced their mechanical properties.An analysis of pore structure indicated that the addition of MSWIT-LA increased the total quantity of pores and promoted cement hydration,resulting in a denser microstructure than that of ordinary concrete.The results of a principal component analysis showed that the mechanical response of specified density concrete prepared with 25%MSWIT-LA was superior to that of an equivalent ordinary concrete.It was therefore concluded that MSWIT-LA can be feasibly applied to achieve excellent specified density concrete properties while utilising municipal solid waste incineration tailings to protect the environment and alleviate shortages of sand and gravel resources.

Physical and mechanical properties of municipal solid waste incineration residues with cement and coal fly ash using X-ray Computed Tomography scanners

A significant volume of Municipal Solid Waste incineration bottom ash and fly ash (i.e.,incineration residues) are commonly disposed as landfill.Meanwhile,reclamation of landfill sites to create a new land space after their closure becomes an important goal in the current fewer and fewer land availability scenario in many narrow countries.The objective of this study is to reclaim incineration residue materials in the landfill site by using cement and coal fly ash as stabilizers aiming at performing quality check as new developed materials before future construction.Indeed,physical and mechanical properties of these new materials should be initially examined at the micro scale,which is the primary fundamental for construction at larger scale.This research examines quantitative influences of using the combination of cement and coal fly ash at different ratio on the internal structure and ability of strength enhancement of incineration residues when suffering from loading.Couple of industrial and micro-focus X-ray computed tomography (CT) scanners combined with an image analysis technique were utilized to characterize and visualize the behavior and internal structure of the incineration residues-cement-coal fly ash mixture under the series of unconfined compression test and curing period effect.Nine types of cement solidified incineration residues in term of different curing period (i.e.,7,14,28 days) and coal fly ash addition content (i.e.,0%,9%,18%) were scanned before and after unconfined compression tests.It was shown that incineration residues solidified by cement and coal fly ash showed an increase in compression strength and deformation modulus with curing time and coal fly ash content.Three-dimension computed tomography images observation and analysis confirmed that solidified incineration residues including incineration bottom and fly ash as well as cement and coal fly ash have the deliquescent materials.Then,it was studied that stabilized parts play a more important role than spatial void distribution in increment or reduction of compression strength.

Effects of seasonal water-level fluctuation on soil pore structure in the Three Gorges Reservoir,China

Inundation of the Three Gorges Reservoir has created a 30-m water-level fluctuation zone with seasonal hydrological alternations of submergence and exposure, which may greatly affect soil properties and bank stability. The aim of this study was to investigate the response of soil pore structure to seasonal water-level fluctuation in the reservoir, and particularly, the hydrological change of wetting and drying cycles. Soil pore structure was visualized with industrial X-ray computed tomography and digital image analysis techniques. The results showed that soil total porosity(? 100 ?m), total pore number, total throat number, and mean throat surface area increased significantly under wetting and drying cycles. Soil porosity, pore number and throat numberwithin each size class increased in the course of wetting and drying cycles. The coordination number, degree of anisotropy and fractal dimension were indicating an increase. In contrast, the mean shape factor, pore-throat ratio, and Euler-Poincaré number decreased due to wetting and drying cycles. These illustrated that the wetting and drying cycles made soil pore structure become more porous, continuous, heterogeneous and complex. It can thus be deduced that the water-level fluctuation would modify soil porosity, pore size distribution, and pore morphology in the Three Gorges Reservoir, which may have profound implications for soil processes, soil functions, and bank stability.

Competitive trampolining influence trabecular bone structure,bone size,and bone strength

Background：Trampolining is a form of gymnastics that has increased in popularity over the last decade and due to its concurrence with the formative years of bone development,it may have an important impact on bone health.However,bone density,microarchitecture,and bone strength of competitive trampolinists have not been explored.Therefore,the purpose of this cross-sectional study was to investigate the relationship between trampolining participation and（1） bone density,area,and microarchitecture;and（2） estimated bone strength and the role of muscle and impact loading in young female adults.Methods：We recruited 29 female participants aged 16–29 years for this study（n=14 trampolinists;n=15 controls）.Skeletal parameters were assessed using dual X-ray absorptiometry,high-resolution peripheral quantitative computed tomography（HR-pQCT）,and finit element analysis（FEA）.Muscle strength was measured using dynamometers.Results：Trampolinists had higher bone density at the hip and spine,greater trabecular density and thicker trabeculae at the tibia,as well as larger bones at both the tibia and radius than controls（p〈0.05）.Trampolinists also had higher muscle strength than controls at the lower body with no difference between groups in the upper body.Estimates of bone strength using FEA were greater for trampolinists than controls at both the radius and tibia.Conclusion：This is the firs study to investigate bone density,area,and microarchitecture in female trampolinists using HR-p QCT.Trampolinists had greater bone density,area,microarchitecture,and estimated bone strength than controls.

Rapid Large Volume 3D Mineral Processing and Liberation Characterization Technique to Sub Micron Resolution

We describe a novel lab based X-ray computed tomography system based on the architecture of X-ray Microscopes (XRM) used in synchrotron radiation facilities to be adapted for mineral processing and mineral liberation analysis. As this is a tomographic technique performed with an XRM, it is non-destructive and does not require complex preparation of polished sections typical of SEM-EDS techniques (such as MLA and QEMSCAN). It complements these existing techniques by providing 3D information and mineral liberation of multi-phase particles with much larger sample volume statistics but at a fraction of the time. In several applications, the technique is superior. These include the characterization of tailing loss in precious minerals; the characterization of porosity, particle size distribution, crack and pore network analysis during comminution, heap leaching and for texture and exposure/lock class analysis for floatation.

双源CT灌注成像在颈部淋巴结病变中的初步研究

目的探讨双源CT灌注成像技术在颈部淋巴结病变定性诊断中的价值。资料与方法对40例颈部肿大淋巴结行CT灌注扫描,将其中34例有完整手术病理结果的病例根据其良恶性分为两组,分析良恶性淋巴结的时间密度曲线(TDC)及灌注参数的特点,比较各灌注参数的统计学差异。结果良性淋巴结组TDC以缓升型为主(87.5%),甲状腺癌转移淋巴结TDC以速升速降型为主(62.5%),淋巴瘤TDC以低平型为主(60%),其他癌(鳞癌、腺癌)转移淋巴结TDC多呈速升缓降型(62.5%);恶性淋巴结组的血流量(BF)、血容量(BV)、Patlak血容量(P-BV)、达峰时间(TTP)及强化值(EV)均高于良性组,其差异有统计学意义(P<0.05)。结论颈部良、恶性淋巴结病变及不同类型恶性淋巴结病变的CT灌注特点不同,CT灌注成像技术对颈部淋巴结病变的定性诊断有重要的应用价值。