Discrete wavelet transforms analysis of vibration signals for correlating tool wear in diamond turning of additive manufactured Ti-6Al-4V alloy

Ultra-precision machining (UPM) of Ti-6Al-4V alloy is widely regarded as a challenging material processing due to excessive tool wear and chemical reactivity of the tool and workpiece. Tool wear has a significant influence on the surface quality and also causes damage to the substrate. Therefore, it is critical to consider the tool condition during diamond turning, especially as precision machining moves toward intelligent systems. Consequently, there is a need for effective ways for in-process tool wear monitoring in UPM. This study aims to monitor the diamond tool wear using time-frequency-based wavelet analysis on vibrational signals acquired during the machining of Additively Manufactured (AM) Ti6Al4V alloy. The analysis employed Daubechies wavelet (db4, level 8) to establish a correlation between the Standard Deviation (SD) of the magnitude in the decomposed vibrational signal obtained from both the fresh and used tools. The analysis revealed that at a feed rate of 1 mm/min, the change in SD is 32.3% whereas at a feed rate of 5 mm/min, the change in SD is 8.4%. Furthermore, the flank wear and microfractures are observed using a scanning electron microscope on the respective flank and rake face of the diamond tool

Leaching of rare earth elements from coal ash using low molecular weight organocarboxylic acids: Complexation overview and kinetic evaluation

The study of thermodynamics and kinetics of leaching rare earth elements (REEs) is a fundamental aspect of understanding the mechanism behind the leaching process. Leaching of REEs from coal ash with an aqueous solution of organocarboxylic acid is a heterogeneous fluid-particle system. In the present study, the leaching mechanisms of these three potential organocarboxylic acids, tartaric acid, lactic acid, and citric acid were examined over a range of temperatures (30-90 degrees C) at various leaching durations. The kinetic data thus obtained were found to follow deviation from the conventional shrinking core model (SCM). A mixed mechanism model was deduced to be the optimum fit to the data with high precision (R-2 > 0.95) and desired graphical linearity with a closer interception to the origin. The aluminosilicate matrix remained unaltered after acid treatment which is the unchanged core concluded from the kinetic mechanism. Morphological analysis using Scanning Electron Microscope (SEM) and particle size determinations were suggestive of a significant reduction in grain size post-leaching with organocarboxylic acids, tartaric acid being the most effective of all

Managing Mining and Minerals Processing Wastes_chapter9

Managing Mining and Minerals Processing Wastes: Concepts, Design and Applications presents fundamental knowledge in waste management in mining and minerals processing and summarizes recent advances. The book offers readers insights into innovative ways to manage waste in the mining and minerals industry. Sections cover a brief introduction to this topic and an explanation of waste generation, and how to manage the six types of waste, including waste rock, mill tailings, coal refuse and coal fly ash, quarry waste, metallurgical slugs and washery rejects. The title then emphasizes the management of hazardous waste, the acid mine drainage and the lifecycle assessment of waste management. Finally, the book considers current and emerging challenges. This publication offers a comprehensive background to waste management in mining and minerals processing and a summary of recent advances and innovative strategies for managing each kind of waste

STUDY ON FLOTATION OF SILLIMANITE USING PLANT-BASED COLLECTOR

In India, the heavy mineral beach sand carry minerals like ilmenite, garnet, rutile, monazite, sillimanite, and zircon. The west coast of Kerala, the east coast from Tamil Nadu to Odisha contains heavy mineral (ilmenite) rich beach sand deposits. These ilmenite samples of Indian origin has 50-60% ofTiO2 and is most suited for beneficia­tion by different processes. Also minerals such as monazite, sillimanite, and zircon are present in inland red Teri sands, apart from heavy mineral beach sands and has high potential for beneficiation. The conducting and magnetic minerals are separated first, leaving behind the non-conducting and non-magnetic sillimanite along with quartz in the processing of heavies in beach sand. The placer minerals of 348 Million tons (Mt) ilmenite, 107 Mt garnet, 21 Mt zircon, 18 Mt monazite, and 130 Mt Sillimanite are present in Indian resources. About 35% of world resources are contributed from India. The heavy mineral sands are basically sedimentary deposits of dense minerals which pile up with sand, silt, and in association with clay along the coastal line, leading to economic concentrations of these heavy minerals [1-5]. The conducting and magnetic minerals are separated first, leaving behind the non-conducting and non-magnetic sillimanite along with quartz in the processing of heavies in beach sand. Sillimanite, an important mineral for refractory application, is mainly recovered by flotation technique from its associated major gangue mineral, quartz by imparting selective surface hydrophobicity on sillimanite using a suitable collector. Sillimanite is a non-conducting and non-magnetic mineral and hence flotation technique was of valuable minerals from its accompanying gangue minerals. Flotation process have been effectively used for fines and size of the sillimanite mineral present in the heavy mineral beach sand is most appropriate to be processed by flotation. In any separation process based on flotation, the flotation reagents added in order to modify/enhance the surface hydrophobic nature of the minerals intended to be separated and hence the appropriate selection of reagent plays a vital role in the efficiency of the flota­tion technique. Apart from the reagent selection, the dosage of the reagents added in the flotation circuits needs to be optimized for the required grade and recovery. Flotation studies on sillimanite by flotation column on Odisha sands were carried out using oleic acid as collector [6-14]. Recovery of sillimanite by flotation tree analysis method and conventional flotation technique from the non-magnetic product of red sediments were also studied. Also, some investigation on flotation of sillimanite at acidic pH were reported. In this work, one such Indian beach placer sample has been attempted for bene­ficiation using flotation method. In preliminary flotation studies, pH and depressant dosage were varied to establish the optimized process criteria. lypes of collectors used for flotation studies are oleic acid and plant-based collector SFA. Flotation of sillimanite sample was optimized by studying various process parameters. Silli­manite feed sample, collectors, and concentrate obtained from optimized set have been characterized using X-ray diffraction (XRD) and Fourier-transform infrared (FfIR) spectroscopy

Distribution, mode of occurrence, and significance of rare-earth elements in coal from Samaleswari open cast coal blocks, Odisha, India with their provenance and paleodepositional environment

This study aims to thoroughly examine the distribution, concentration, and occurrence of a broad selection of REEs and major elements in coal samples from Samaleswari coal block, IB valley, Odisha, India using advanced geochemical tools. A total of 85 coal samples from four boreholes were characterized using proximate analysis and calorific value measurements. The corresponding ash samples were examined using X-ray Diffraction (XRD), X-ray Fluorescence (XRF), Electron Probe Microanalyzer (EPMA), and Inductively Coupled Plasma Mass Spectrometry (ICP-MS).The coal ash samples were delineated to be rich in SiO2 (42-65%) along with a lower proportion of Al2O3 (24-41%), Fe2O3 (5-6%), and TiO2 (1-2%). The average concentration of REEs in the four boreholes was found to be 510 ppm, with the distribution pattern being Ce > La > Nd > Y > Pr > Sc > Sm > Gd > Dy > Er > Yb > Eu > Ho > Tb > Tm > Lu. The concentration of critical REEs varied in the range of 100-300 ppm, and outlook coefficient (C-outl) ranged from 0.7 to 1.0, demonstrating our coal seams' suitability as a promising source of REEs. A higher concentration of REEs in BH1 was correlated with a relatively higher proportion of apatite. The increment in REE concentration with depth was speculated to be due to their close association with hematite, especially in BH1 and BH2. A strong positive correlation of all the REEs with clay minerals and specifically TiO2 reinstates their abundance in fine-grained clastic sedimentary rocks which are not significantly affected by weathering. Point analysis using EPMA and Scanning Electron Microscope-Energy Dispersive Analysis X-ray (SEM-EDAX) confirmed the co-existence of La, Ce, Pr, and Nd in the Fe-containing aluminosilicate matrix. In addition, the major oxide ratio and their plot entail terrestrial depositional environment in the basin during coal formation and deposited in semi-arid climatic conditions

Modeling and optimization of green-Al 6061 prepared from environmentally source materials

Recent studies are evaluating the use of particulates fabricated from agro-based residues as reinforcement for enhancing the properties of aluminium alloys. This report focuses on the optimization approach and modeling of responses for future prediction, which are absent from the majority of studies involving particle reinforcement of an aluminum matrix. Herein, palm kernel shell ash (PKA) and rice husk ash (RHA) were incorporated with 4 wt% of WSD and used as fillers in the Aluminium-6061 matrix at variable proportions. The response surface approach was utilized in the experiment design, modeling, and outcome optimization. The independent variables are the proportions of PKA and RHA and stir casting temperature. Yield, ultimate tensile, impact strength, elastic modulus, and fracture toughness are examined as response parameters. The results demonstrated that the microstructural property played a significant role in the responses. Incorporating PKA and RHA into the Al-6061 matrix improved the response parameters. Temperatures in the range of 700 and 800 degrees C enhanced the property parameters, even though temperatures within 800 and 900 degrees C caused a decline in response. The dependence of the responses on the pattern between property variables was revealed by surface and contour plots. The development of models for predicting responses. Optimal conditions were reached at 4.03% PKA, 5.12% RHA, and 787 degrees C, with an error of <5% when compared to the forecast responses, thus validating the model

Validation of Bromide Leaching through Response Surface Methodology and Separation of Gold from Waste Printed Circuit Boards

The daily consumption of gold is increasing worldwide; however, its availability from conventional ores is reducing. Alternatively, the presence of gold in waste electrical and electronic equipment (WEEE) is nearly 100 times higher than in natural ore. Therefore, the possibility of the recovery and separation of gold from waste printed circuit boards of obsolete mobile phones is studied in the present work. Initially, the optimization of parameters for the quantitative gold leaching from metal clads of PCBs with halide salts at acidic conditions is studied through response surface methodology. Three factors (parameters), viz. temperature, time and stirring speed are altered during the experiments based on the central composite design (CCD). Leaching parameters have been optimized with the help of the second-order empirical equations and analysis of variance (ANOVA) for maximum gold dissolution. The selective recovery and separation of gold from leach liquor have been achieved with solvent extraction with an organic amide as extractant followed by cementation with zinc powder. The separated gold powder has also been analyzed with XRD and SEM-EDS to check the purity and homogeneous elemental distribution. The statistical design of experiments and separation processes for the effective recovery of gold corroborates the economic feasibility of the proposed process

Failure Investigation of Boiler Tube: A Root Cause Analysis

In a thermal power plant, water wall boiler tube made of Cr–Mo low alloy steel, failed during operation. Post failure investigation revealed ‘fish mouth’ opening accompanied by thick scale formation, significant wall thinning and de-shaping of circular cross section of tube material. All the evidence indicated temperature rise over a period, for which martensitic transformation, matrix grain growth and globulerization of carbide precipitate occurred within microstructure of the alloy. The temperature rise was due to the over-firing of burner and the sudden change in flue gas constituents. Wall thinning due to oxide scale formation and plastic flow of material at elevated temperature tentatively below upper critical temperature, reduced the load bearing ability of component. The tube material ultimately failed due to overload during service

A Comprehensive Review on Occurrence and Processing of Phosphate Rock Based Resources- Focus on REEs

In general, the phosphatic rock contains around 0.05 wt% rare earth elements (REEs). The global commercial phosphatic rock output is anticipated to obtain 250 million tons per year, making phosphate rocks a significant source of REEs. The review discusses the geological aspects of phosphate rocks, their availability, and methodologies to convert them to phosphoric acid and ultimately to phosphogypsum. Phosphogypsum (PG) is a high-volume by-product of phosphate-based chemical industries that produce phosphoric acid. Because of the low radioactivity of radionuclide contaminants, roughly 85% of PG is stored in open fields. These PG stacks require enormous land areas, cause substantial upkeep expenses, and may create major environmental damage. Apart from the detailed analysis of metal worth in phosphogypsum, the efforts put forth by researchers in recovering valuable rare earth elements from PG have been discussed. Additionally, the processes for metal separation and purification are also discussed in vogue

Carbon dioxide sequestration by mechanical activation of Linz-Donawitz steel slag; the effect of water on CO2 capture

Mineral carbonation, a process of carbon-dioxide (CO2) captured from the atmosphere or flue gases, is a way to sequestrate CO2 safely and permanently. In this technology, CO2 is chemically reacted with calcium, magnesium, sodium, and iron-containing materials. The procedure is analogous to natural weathering processes, to form thermodynamically stable and environmentally harmless carbonate minerals. Our research was focused on simultaneous mechanical activation and CO2 capture and storage (CCS) on Linz-Donawitz steel slag dominantly composed of Ca-silicate and oxide phases. The experiments were carried out in a planetary ball mill under 5 bar CO2 pressure in dry and wet (deionized H2O) conditions. The primary objective of the experiments was to observe the role of H2O in the reactions. The presence of H2O in the system leads to a finer particle size distribution but, at the same time, reduces the number of active sites·H2O also acts as a carbonate reaction promoter, it is expected to initialize silicate (Windt et al. 2010) surface protonation and enhancing Ca leaching. The latter of the two processes was predominant so that in wet condition (0,246 kgCO2/kg), almost three times as much calcite is produced as in dry condition (0,083 kgCO2/kg). The combination of nano milling and wet media carbonation is a promising process to reduce energy requirement through increasing the reaction rate and promotes the use of Ca-silicate wastes otherwise underperforming in CCS