Abstract Comminution is a critical stage of mineral processing which aims to reduce the size of ore particles through breakage, consequently increasing the likelihood of the liberation of valuable minerals. However, comminution is highly energy-intensive, and an understanding of the key breakage mechanisms has been identified as an important factor in improving the efficiency of the process. Several factors, such as pre-existing cracks, mineralogical composition, ore shape and size are known...
Abstract The Fischer-Tropsch synthesis (FTS) process, better known for its ability to produce synthetic fuel via the hydrogenation of CO, has shown potential to produce valuable chemicals when ammonia is added to the feed. In this work certain aspects of the pathway to the formation of N-containing compounds that form when NH3 is added during FTS, using mostly iron based catalysts is investigated. In addition, the effect this has on the FTS reaction itself is evaluated. To achieve this goal, ...
Abstract Within froth flotation, it is widely acknowledged that froth stability affects flotation performance. As a result, it is expected that through the effective management of froth stability, it would be possible to both control and optimise a flotation cell and bank. However, for this to be possible, the relationships between the operating conditions, froth stability behaviour and flotation performance attributes need to be well understood. In addition, froth stability would need to be ...
ABSTRACT The effect of impurities on the precipitation behaviour of nickel powder produced by high-pressure hydrogen reduction was investigated in order to determine the factors responsible for the formation of powder with undesirable morphology. In nickel precipitation by hydrogen reduction, two product morphologies have been observed: the spherical, open powder (desirable) and the spherical, closing/closed powder (undesirable). Two major impurities were studied namely; a morphology modifie...
More recently, Solvent Extraction of Copper from aqueous solution has been an area for considerable research and development. The present programme has gone a stage further by investigating the separation of copper from mixed solutions cf copper and iron in Electrical fields. The work was carried out in a countercurrent column which gave differential as opposed to the stage contact of previous workers. Continuous transfer of material between phases occurs resulting in the differential change ...
The US Environmental Protection Agency (EPA) issued the first ever federal rule to permanently cap and reduce mercury emissions from coal-fired power plants on March 15, 2005. The rule referred to as The Clean Air Mercury Rule (CAMR) when fully implemented, will reduce utility emissions of mercury from 48 tons a year to 15 tons by 2018, a reduction of nearly 70%. These mandatory declining caps coupled with significant penalties for noncompliance, will ensure that mercury reduction requir...
Some industrial equipment such as electric tranformers and capacitors are located in vaults and substations on flat concrete surfaces. Due to accidents, normal routine maintenance, or replacements, this equipment may spill oil that may contain PCBs on these surfaces. These spills must be cleaned up in accordance with United States Environmental Protection Agency's (USEPA) guidelines. Current cleanup operations are abiotic in nature, encompassing both physical and chemical methods. These metho...
ABSTRACT In this study, hydrodesulphurization (HDS), hydrodenitrogenation (HDN), hydrodemetallization (HDM), and micro carbon residue (MCR) renoval were investigated using residuum hydrocracking catalysts containing a zeolite component. It to well known that the strong Brønsted acid sites on the external surfaces of zeolite crystals increase the distillate yield and decrease the coke yield obtained when using fluid catalytic cracking (FCC) catalysts. However, comparatively few studies have b...
ABSTRACT Oilseed sunflower is one of the major vegetable oil sources. The residue after the extraction of oil (defatted meal, DM) contains a substantial amount of nutritious protein which is recoverable by extraction and precipitation methods. For effective recovery of the solid proteins from the solids-liquid suspension, it is imperative to have large particles with a narrow spread in their size distribution and high solids concentration. In this research, up to 97 % w/w and 65 % w/w of the...
ABSTRACT The increasing demand for silver nanoparticles has led to the need for new superior methods of synthesis to be developed. In this study, the Allium Ascalonicum plant was used in the plant-mediated synthesis of silver nanoparticles. The phytochemicals of the plant were extracted using seven different solvents with a range of polarities and the methanol/water 50/50 solvent had the highest extraction yield of 63 %. The phytochemical tests showed that the plant is rich in phytochemicals ...
ABSTRACT A green approach was used in the synthesis of silver nanoparticles which is an easy, cheap, eco-friendly and a fast method in achieving stable silver nanoparticles over a long period of time. Plant leaves extract from Parinari Curatellifolia and Vangueria Infausta were used in the synthesis after optimizing different parameters (temperature, silver nitrate concentration and amount of extract. The optimum conditions achieved for the synthesis of silver nanoparticles (AgNPs) using Pari...
ABSTRACT Biological and antioxidant activities of Dicoma anomala, Kigelia pinnata, Pseudolachnostylis maprounelifolia and Flacourtia indica are reported. The medicinal plant extracts of different polarities were prepared and tested for antimicrobial activity using the disc diffusion method. The acetone crude extracts showed the highest activity as compared to the chloroform and petroleum ether extracts. The qualitative analysis of the extracts showed presence of tannins, saponins, phenolics, ...
ABSTRACT A comparative analysis of the efficiency of activated carbon produced from Berchemia discolour seed shells derived activated carbon (BDSAC) and commercial grade activated carbon (Haycarb Carbon) was utilized in the adsorption of gold (iii) chloride from acidic medium. The adsorption process of BDSAC was best described by the Freundlich, Halsey, Dubinin Radushkevich (D R), Temkin isotherms and Langmuir isotherm had RL values in the range 0 < RL < 1 hence the adsorption process was fav...
ABSTRACT Ascorbic acid and dopamine are biomolecules found in humans. They both have important functions in the body and cause numerous side effects at high concentrations. An electrochemical sensor based on nickel( II) tetra amino phthalocyanine conjugated to iron oxide doped graphene oxide nanosheets was developed.FTIR,UV- vis, cyclic voltammetry ( CV) and electrochemical impedence spectroscopy (EIS) were used for characterisation of electrode modifiers.FTIR was used to ascertain that a che...