-
Spatial Correlation of the Backscattered Ultrasonic Grain Noise in the Ultrasonic Inspection of the Forging Titanium Alloy
Theodor Tranca,
Iuliana Radu
Issue:
Volume 6, Issue 3, September 2021
Pages:
33-40
Received:
14 June 2021
Accepted:
5 July 2021
Published:
15 July 2021
Abstract: Ultrasonic inspection is a routine Non Destructive Examination (NDE) method adopted by the aircraft engine manufacturers. However, the detection of smaller defects in such materials is made difficult by the complicated ultrasound-microstructure interactions. One of the adverse influences of the interactions is the high backscattered grain noise level accompanying with the ultrasonic inspections of some titanium alloys. The high grain noise deteriorates the Signal to Noise ratio (S/N) of pulse/echo inspections and consequently may lead to the missing detection of an existing flaw. Ultrasonic signal fluctuations have direct impact on flaw detection, flaw characterization and the estimation of the Probability of Detection (POD). The total backscattering is controlled by grain morphology, grain orientation and elastic anisotropy, which may vary throughout the microstructure. Thus any Thermo-Mechanical Processing (TMP) leading to the variations of material microstructure may influence the backscattered grain noise. We developed new ideas of how to extract useful microstructural information from the forging simulation software Simufact.forming, a commercial software package produced by Simufact Engineering GmbH. A model is then developed to correlate the grain noise signals with the microstructural variations due to the inhomogeneous plastic deformation associated with the forging processing. The grain noise levels predicted by the model at various locations are compared with experiments. Reasonably good agreements are observed.
Abstract: Ultrasonic inspection is a routine Non Destructive Examination (NDE) method adopted by the aircraft engine manufacturers. However, the detection of smaller defects in such materials is made difficult by the complicated ultrasound-microstructure interactions. One of the adverse influences of the interactions is the high backscattered grain noise lev...
Show More
-
The Reduction of Chrome in UG-2 Flotation Concentrate by Hydrometallurgical Means
Abel Monele Mokadze,
Sehliselo Ndlovu,
Alan Shemi,
Marek Dworzanowski
Issue:
Volume 6, Issue 3, September 2021
Pages:
41-52
Received:
7 July 2021
Accepted:
29 July 2021
Published:
4 August 2021
Abstract: The South African platinum industry has advanced into an era of predominantly mining and processing Upper Group Two (UG-2) ore to extract Platinum Group Metals (PGMs). Flotation concentrates derived from processing UG-2 ore are typically characterized by high chrome contents (>3 wt.%) which are not amenable to conventional PGM smelters. The net effect of high chrome, inter alia, includes increased smelting energy requirements and the reduction of effective furnace capacity. Various interventions ranging from the redesign and modification of existing physical and pyrometallurgical operations have been introduced and these have yielded no sustainable solutions. In this study, a hydrometallurgical process was investigated as an alternative route to reduce chrome in UG-2 concentrates. The parameters initially considered for investigation were acid concentration, leaching time, temperature and oxygen flowrate while keeping solid to liquid ratio and agitation rate constant. Results showed that oxygen flowrate and an interaction of temperature, time and acid concentration had a positive but minimal effect on Cr extraction. The highest Cr extraction obtained was 7.0%. Further test work entailed exploring the effect of solid to liquid ratio using optimized conditions. The results showed a substantial increase of Cr extraction of up to 37%. This represents 1.33% decrease in chrome content, from 3.63% to 2.30%, in UG-2 concentrate.
Abstract: The South African platinum industry has advanced into an era of predominantly mining and processing Upper Group Two (UG-2) ore to extract Platinum Group Metals (PGMs). Flotation concentrates derived from processing UG-2 ore are typically characterized by high chrome contents (>3 wt.%) which are not amenable to conventional PGM smelters. The net eff...
Show More
-
Bauxite Mining Conflicts in Guinea: Causes Identification, Analysis, and Countermeasures
Issiagha Camara,
Jiang Deyi,
Oumar Barry,
Frederick Caille
Issue:
Volume 6, Issue 3, September 2021
Pages:
53-66
Received:
5 August 2021
Accepted:
17 August 2021
Published:
27 August 2021
Abstract: Mining conflicts are among the most widespread issues linked to natural resources development and management in mineral-rich countries. Guinea mining industries development presents a huge challenge in promoting integrated, prosperous, peaceful, and sustainable mining. The scramble of companies to exploit bauxite in the Boké region is correlated with a wave of protests and violent conflicts. This article explores the reasons for the resurgence of conflicts in the Guinea Republic, proposes some strategies for better mining conflicts prevention, management in Boke region. Thus, through a survey carried out in 7 Municipalities of the region and other mining localities of the country, we use a quantitative approach through descriptive statistic elements to identify the causes of the outburst of the conflict in Boke which seriously hinders the climate of socioeconomic activities for local development. The outcomes of this study reveal that youth employment, water and electricity supply, the weakness in the management of compensation mechanism are the main reasons for conflict escalation in Boke. Although, solutions proposed by the state and some NGOs appear to be hopeful. However, better management of public services and good governance based on more innovative public-private partnerships, and changes in government policy to better benefit the local communities could solve these problems holistically. The implementation of a better strategy (approach) in the management of relations with the surrounding communities by considering the depths and the sociohistorical, cultural, economic characteristics of the region would guarantee an environment of peaceful cohabitation between the local communities and the companies.
Abstract: Mining conflicts are among the most widespread issues linked to natural resources development and management in mineral-rich countries. Guinea mining industries development presents a huge challenge in promoting integrated, prosperous, peaceful, and sustainable mining. The scramble of companies to exploit bauxite in the Boké region is correlated wi...
Show More
-
Reducing Uncertainties in Gold Plant Design and Operations
Charles Amoah,
Grace Ofori-Sarpong,
Richard Kwasi Amankwah
Issue:
Volume 6, Issue 3, September 2021
Pages:
67-72
Received:
1 September 2021
Accepted:
16 September 2021
Published:
27 September 2021
Abstract: The conventional way of designing a plant is to determine the characteristics of rocks in terms of crushability, grindability and other properties that affect the mill throughput. These properties are most of the time determined from drill cores obtained during the exploration period. Such initial exploration campaigns drill to levels shallower than the real pit that will be developed. Thus, as mining pits become deeper, the ore characteristics change and begin to impact negatively on the expected mill throughput. Such situations necessitate modification of the plant, and the first intervention usually is to supplement the initial energy input with additional size reduction equipment to achieve the required throughput. However, reconsidering the inputs used in determining the initial plant selection would help in reducing the setbacks during the operational period. To help reduce uncertainties and develop a predictive tool, this study considered a greenfield drilled up to 273 m, and the core samples obtained were tested to ascertain the variations in Bond work index to depths beyond 500 m. The study showed that within the section of the Asankragwa belt investigated, Bond work indices increased from 10.3 kW/t at the surface to 16.5 kW/t at a depth of 273 m. The Bond work index was established as a function of vertical depth in a pit (x) with the relation BWI=6E-05x2 + 0.0071x + 9.8816. The predicted value at 280 m was 16.3 kW/t while that of the blend was 15.8 kW/t, giving an error of 4%. This novel relationship between the BWI and depth predicts the BWI beyond 500m with minimum mean square error. The use of the novel Bond work index and depth relationship will eliminate the uncertainty beyond the drilled depth and give a clear understanding of what the rock characteristics will be as pits become deeper. In addition, a savings of US$62,500 per diamond drill hole and US$25,000 per one reverse drilling after the 250 m depth can be made by the use of this model. This can result in massive savings considering the number of holes that would have to be drilled across the length of the pit.
Abstract: The conventional way of designing a plant is to determine the characteristics of rocks in terms of crushability, grindability and other properties that affect the mill throughput. These properties are most of the time determined from drill cores obtained during the exploration period. Such initial exploration campaigns drill to levels shallower tha...
Show More
