Ed Hardwick

• BSc
• Research Director at Cwenga

Cwenga Technologies and Tongaat Hulett investigated the effectiveness of reactivated Granular Activated Carbon (GAC) as an economically friendly alternative to virgin GAC for fructose syrup decolourisation. Reactivation occurs when spent activated carbon undergoes thermal treatment, which removes loaded organics from the carbon pores. The key par...

Recovery of rare earth elements from acid mine drainage using strong acid cation resin, and separation by green chemistry methods

Inductively coupled plasma optical emission spectroscopy (ICP-OES) and mass spectrometry(ICP-MS) are suitable techniques for trace multiple-element analysis but may have difficulty withthese analyses when samples comprise complex matrices (due to spectral interference and matrixeffects). High iron concentrations (>3 g/L) in acid mine drainage (AMD)...

Rare earth elements (REEs) are crucial in multiple industrial applications, but their limited distribution in the Earth's crust has led to worldwide supply shortages. A sustainable alternative is recycling REEs from waste streams, such as mine-impacted water. This study examined the REE concentration in coal mine acid mine drainage (AMD) and used i...

Rare earth elements (REEs) are crucial in multiple industrial applications, but their limited distribution in the Earth's crust has led to worldwide supply shortages. A sustainable alternative is recycling REEs from waste streams, such as mine-impacted water. This study examined the REE concentration in coal mine acid mine drainage (AMD) and used i...

Nitrates in drinking water are becoming a major problem. According to the World Health Organization (WHO) and South African National Standard (SANS) (SANS 241: 2011) the maximum concentration limit of nitrogen is 50 ppm and 49 ppm as nitrate, 11.3 ppm and 11 ppm as Nitrate-nitrogen, respectively. From literature it is stated that nitrates and nitri...

Lithium-ion battery (LiB) demand has increased with advancement in technical applications such as electric vehicles, cell phones, laptops and many more rechargeable devices. Typical components of the cathodes include lithium, cobalt, nickel and manganese. Recycling of the spent LiBs is necessary to reduce the ecological footprint of their productio...

In November 1978 the bone char decolourisation plant at Tongaat-Hulett Refinery (Hulref) was replaced with five ion-exchange columns. This change had major benefits for the refinery in terms of chemical and energy costs, and refined sugar quality. In order to improve the liquor decolourisation, a further five secondary stage resin columns were inst...

It was identified that a number of ion exchange demineralisation plants in Southern Africa were being operated sub-optimally for the current water conditions. Often the cause is due to deteriorating water quality and the loss of experienced operators. The result of this is an increase in operating costs and a higher environmental impact. The audit...

A study was completed at a stainless steel manufacturer to recovery valuable materials from the spent pickling liquor before the effluent treatment plant. The existing process consists of lime neutralisation followed by filtration and evaporation. Large amounts of metal and Fluoride containing solids were lost. A laboratory scale study using ion ex...

Both ion exchange resin and activated carbon are well established technologies used in final stage decolourisation of sugar liquors for the production of high quality white sugars. These technologies are often seen to be in direct competition, but there are unique advantages and disadvantages to both, and they are applicable in different circumstan...

Ion exchange has traditionally been employed for water purification and the removal of metal contaminants from dilute waste streams. More recently, its use in removing trace metallic impurities from hydrometallurgical process streams (with typical background metal concentrations of 50–100 g/L) has increased substantially. It is also used as a prima...

During the 1999-2000 off-crop season, a Granular Activated Carbon (GAC) system with a reactivation facility was installed at Nchalo mill to replace the existing sulphitation process for sugar decolourisation. In 2001, a paper was presented at SASTA by Illovo on the operation and performance of the GAC Plant at Nchalo over its first season of operat...

Sugar solutions have been treated with ion exchangers for over a century. Originally the aim was to reduce the cation content in order to increase the sugar yield. The development of far more efficient ion exchanger resins based on styrene / divinylbenzene copolymers and crosslinked polyacrylamides, has considerably increased both the yield and the...

Two copper-containing waste-water streams from a Chilean mine site were identified as potential sources of revenue: Source 1 is raffinate from a copper solvent-extraction circuit; Source 2 originates from a reservoir receiving acid mine drainage as a result of natural snow melt. The streams are currently treated with lime to increase the pH for pro...

This paper provides an overview of the potential for recovery of value from contaminated mine waters and waste streams. It discusses various metal ions commonly found in acid mine drainage and other mine waters (mainly Co, Ni, Zn, and U) and evaluates at what concentration they become attractive to investigate for recovery using ion-exchange techno...

The design and results of a continuous pilot-plant trial to remove copper and zinc to levels of <1 mg/L from the cobalt electrolyte are described. Copper is removed first using an iminodiacetic-acid resin; following pH adjustment, zinc is then removed using an aminophosphonic-acid resin. This paper discusses the flowsheet configuration selected, pr...

Ion exchange has traditionally been employed for water purification and for the removal of metal contaminants from waste-waters or dilute streams. In the last 25 years, however, its use for removing various trace metallic impurities from hydrometallurgical process streams (with background metal concentrations typically ranging from 50 to 100 g/L) h...

BACKGROUND Changes to the process flowsheet and increasing zinc content of the feed materials to the Anglo American Platinum Rustenburg Base Metals Refinery circuit resulted in increasing deportment of zinc to the nickel product and necessitated a dedicated zinc-removal circuit to ensure continued consistent quality of the nickel cathode.RESULTSThe...