Dr Alex Riley

Professional Certificate in Academic Practice
FHEA

Status Complete

Part Time Yes

Years 2021 - 2023

Awarding Institution University of Hull

Status	Complete
Part Time	Yes
Years	2021 - 2023
Awarding Institution	University of Hull

PhD Chemical & Biological Engineering
PhD / DPhil

Status Complete

Years 2016 - 2020

Project Title Targeted Resource Recovery from Mine Waters by Selective Ion Exchange

Project Description Waste stockpiles generated as a result of mining cause long-term damage to the environment and can continue to act as a source of pollution for decades beyond mine closure. Current treatment options tend to focus predominantly on Fe removal and may not properly target other trace metal species that may also be present, e.g. Ni, Mn, Co, Cu; metals with an intrinsic recovery value. As such, this thesis explores the potential application of ion exchange resins to selectively recover metals from mine waters, with the hope that by viewing the wastes as a resource rather than a problem, an incentive is provided to deal with this globally significant pollution source.
A range of commercially available ion exchange resins of different chemical functionality were screened for their selective metal recovery performance under a range of pH and [SO42-] conditions. Of the most suitable resins, fixed-bed breakthrough modelling was used to describe their extractive abilities under dynamic operation, and to define optimum operating conditions. Of particular note, a resin was identified which was capable of truly selective Cu recovery from the complex waste stream. The extent to which metals could be recovered from resins after extraction was determined through elution studies, and the composition of eluents was tailored to maximise the concentration of solutions recovered. For one of the resins, a two-stage elution process was proposed for the selective recovery of Co and Ni as two separate, concentrated product streams; a highly desirable separation given the high value of each metal. The reusability of each resin was determined through cyclic adsorption and desorption studies to assess process sustainability, and where appropriate, resin degradation mechanisms were explored. Finally, a bench-scale system was operated to explore the potential of a coupled-column system design for continuous treatment and resource recovery.

Awarding Institution University of Sheffield

Status	Complete
Years	2016 - 2020
Project Title	Targeted Resource Recovery from Mine Waters by Selective Ion Exchange
Project Description	Waste stockpiles generated as a result of mining cause long-term damage to the environment and can continue to act as a source of pollution for decades beyond mine closure. Current treatment options tend to focus predominantly on Fe removal and may not properly target other trace metal species that may also be present, e.g. Ni, Mn, Co, Cu; metals with an intrinsic recovery value. As such, this thesis explores the potential application of ion exchange resins to selectively recover metals from mine waters, with the hope that by viewing the wastes as a resource rather than a problem, an incentive is provided to deal with this globally significant pollution source. A range of commercially available ion exchange resins of different chemical functionality were screened for their selective metal recovery performance under a range of pH and [SO42-] conditions. Of the most suitable resins, fixed-bed breakthrough modelling was used to describe their extractive abilities under dynamic operation, and to define optimum operating conditions. Of particular note, a resin was identified which was capable of truly selective Cu recovery from the complex waste stream. The extent to which metals could be recovered from resins after extraction was determined through elution studies, and the composition of eluents was tailored to maximise the concentration of solutions recovered. For one of the resins, a two-stage elution process was proposed for the selective recovery of Co and Ni as two separate, concentrated product streams; a highly desirable separation given the high value of each metal. The reusability of each resin was determined through cyclic adsorption and desorption studies to assess process sustainability, and where appropriate, resin degradation mechanisms were explored. Finally, a bench-scale system was operated to explore the potential of a coupled-column system design for continuous treatment and resource recovery.
Awarding Institution	University of Sheffield

MSc Biological Sciences
MSc

Status Complete

Years 2014 - 2015

Project Title Contaminant Dynamics and Trends in Highly Alkaline Steel Slag Leachates

Project Description The disposal of slag generated by the steel industry has numerous negative effects on the surrounding aquatic environment through alteration of pH to hyperalkaline levels, the leaching of potentially problematic trace metals, and enhanced rates of precipitation of secondary phase minerals which smother benthic habitats. Data are presented from analysis of a 36-year dataset of ambient monitoring of physiochemical parameters and elemental composition of waters from two streams draining steel slag mounds in Consett, County Durham. Samples were characterised by highly alkaline pH (>10), high alkalinity, and were rich in dissolved metals. Temporal trend analysis was performed on pH, alkalinity, and Ca concentration which were used in conjunction with Ca flux calculations to highlight the longevity of pollution following environmental disposal of steel slag. Assuming continuation of observed trends, it is estimated that 50-80 years will be required before calcite precipitation would reach baseline levels. Spatial analyses of changes in solute loadings downstream of leachate input are also presented to improve our understanding of contaminant behaviour in these systems. Through geochemical modelling and statistical analysis, significant attenuation of metals was associated with the precipitation/co-precipitation of metal(oids) (e.g. V, Sr) with rapidly-forming secondary phase minerals in close proximity to leachate emergence. Mass balance estimates were used to quantify the effect of contaminant attenuation on a long-term scale, and revealed high attenuation of metals in the years since active operation ceased at the site, particularly Fe (>660 tonnes (T)), Al (>1176 T), and Ca (>1983 T). The carbon sequestration downstream of one slag-affected stream is also significant (> 2280 T). These new insights into long term solute dynamics are discussed with respect to long term environmental management of steel slag disposal sites.

Awarding Institution University of Hull

Status	Complete
Years	2014 - 2015
Project Title	Contaminant Dynamics and Trends in Highly Alkaline Steel Slag Leachates
Project Description	The disposal of slag generated by the steel industry has numerous negative effects on the surrounding aquatic environment through alteration of pH to hyperalkaline levels, the leaching of potentially problematic trace metals, and enhanced rates of precipitation of secondary phase minerals which smother benthic habitats. Data are presented from analysis of a 36-year dataset of ambient monitoring of physiochemical parameters and elemental composition of waters from two streams draining steel slag mounds in Consett, County Durham. Samples were characterised by highly alkaline pH (>10), high alkalinity, and were rich in dissolved metals. Temporal trend analysis was performed on pH, alkalinity, and Ca concentration which were used in conjunction with Ca flux calculations to highlight the longevity of pollution following environmental disposal of steel slag. Assuming continuation of observed trends, it is estimated that 50-80 years will be required before calcite precipitation would reach baseline levels. Spatial analyses of changes in solute loadings downstream of leachate input are also presented to improve our understanding of contaminant behaviour in these systems. Through geochemical modelling and statistical analysis, significant attenuation of metals was associated with the precipitation/co-precipitation of metal(oids) (e.g. V, Sr) with rapidly-forming secondary phase minerals in close proximity to leachate emergence. Mass balance estimates were used to quantify the effect of contaminant attenuation on a long-term scale, and revealed high attenuation of metals in the years since active operation ceased at the site, particularly Fe (>660 tonnes (T)), Al (>1176 T), and Ca (>1983 T). The carbon sequestration downstream of one slag-affected stream is also significant (> 2280 T). These new insights into long term solute dynamics are discussed with respect to long term environmental management of steel slag disposal sites.
Awarding Institution	University of Hull

BSc Environmental Science
BSc

Status Complete

Years 2011 - 2014

Awarding Institution University of Hull

Dr Alex Riley's Qualifications (4)