XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 1635
extractants. We are focusing on tuning bio-solvents that
can effectively remove silica, aluminum, magnesium, and
calcium present in silicates, such as kaolinite and other sec-
ondary alumino-silicates. Gangue removal has the potential
to improve metal recovery (e.g., through improved sepa-
ration via flotation), upgrade ores and concentrates, and
remove components that negatively impact downstream
processing, such as smelting.
The natural generation of calcite minerals is a ubiq-
uitous process found in a wide range of environments
(Naveed et al., 2020). One such process is known as micro-
bially-induced carbonate precipitation (MICP). Its coun-
terpart, where enzymes are separated from the microbes for
use, is known as enzyme-induced carbonate precipitation
(EICP). Biocementation is rapidly expanding in the field
of environmental engineering and relevant applications of
this technology include soil stabilization, erosion control,
dust suppression, groundwater remediation, construc-
tion material fabrication and restoration, and toxic metal
immobilization (Mujah et al. 2017, Proudfoot et al. 2022,
Song et al., 2022). We are developing both enzymatic and
microbial approaches (EICP and MICP) for agglomerating
and controlling the strength and geotechnical stability of
a range of materials, including ore stockpiles and tailings.
Finally, several microbially-mediated processes, including
MICP and EICP, have the potential when applied to min-
ing materials to sequester CO2, therefore opening addi-
tional doors for meeting sustainability goals (Grayevsky et
al. 2023, Mirjafari et al. 2007, Ni et al. 2023, Okyey et al.,
2016).
EXPERIMENTAL
Bio-Solubilization
Allonnia is evaluating a range of bio-solvents for their abil-
ity to selectively solubilize gangue minerals, and remove
aluminum (Al), silica (SiO2), calcium (Ca), and magne-
sium (Mg) from the solids. The bio-solvents are composed
of microbial metabolites present within individual bacteria,
fungi, and/or microbial consortia that have shown poten-
tial for selective solubilization in natural and laboratory
conditions.
We have extended solubilization experiments across a
range of ore types, concentrates, tailings, and individual
minerals to understand baseline bio-solvent performance
and key operational parameters. The results presented in
this paper include an ore material that has been pulverized
to a P95 of 106 microns, a flotation concentrate and silica-
rich tailings with similar size distributions. Operational
parameter evaluations have included solid loading (5 to
30% solids by weight) and a range of temperatures (30 to
80°C) under well-stirred conditions.
The data presented in this paper were analyzed by a
commercial analytical laboratory using lithium borate
fusion disks measured on a wavelength dispersive X-ray flu-
orescence spectrometer (WD-XRF) and semi-quantitative
estimates of mineralogy were determined by X-ray diffrac-
tion (XRD) using the Rietveld refinement method. Both
methods included industry-standard QA/QC reporting
requirements.
BIO-CEMENTATION
Allonnia is evaluating promising microbes from our bio-
bank for MICP ability with a goal of also limiting urea
and Ca additions to create more economic, sustainable,
and environmentally friendly bio-cement formulations.
In addition, we are exploring applications for EICP and
the production of microbial enzymes at scale for mining
applications. As part of our experimental work, we have
been testing baseline reaction conditions and developing
cementation formulas and deployment strategies. We are
exploring key factors such as curing time, moisture content,
enzyme activity, temperature, and pressure on unconfined
compressive strength achieved through the biocementation
of mining materials. Further, we are testing the ability of
the ore and tailings bio-cement to withstand variable envi-
ronmental conditions (e.g., heat and moisture) and explor-
ing how different materials may inhibit these carbonation
reactions. These factors will determine the efficacy of the
calcite precipitation process for various mining applica-
tions including stockpile protection from the elements,
dust control, and liquefaction control for tailings and cargo
stabilization. We are testing additional biological additives
to reach target values for parameters such as strength and
moisture content.
CO2 SEQUESTRATION
Building from both our bio-solubilization and bio-cemen-
tation work, Allonnia is looking into the potential to use
microbial processes for carbon capture. While the ureolytic
pathway is the most commonly employed EICP/MICP
reaction, carbonic anhydrase catalyzes the reaction of CO2
and water into bicarbonate which can then react with cat-
ions such as Mg and Ca to create carbonates, thus remov-
ing CO2 from the atmosphere and storing it in a stable
form. Both concentrated CO2 and cations (e.g., Mg and
Ca) sources are abundant in the mining industry. In addi-
tion, we are exploring alternative carbon capture methods,
for example by inducing the complexation of microbially
produced metabolites with a range of solubilized gangue
extractants. We are focusing on tuning bio-solvents that
can effectively remove silica, aluminum, magnesium, and
calcium present in silicates, such as kaolinite and other sec-
ondary alumino-silicates. Gangue removal has the potential
to improve metal recovery (e.g., through improved sepa-
ration via flotation), upgrade ores and concentrates, and
remove components that negatively impact downstream
processing, such as smelting.
The natural generation of calcite minerals is a ubiq-
uitous process found in a wide range of environments
(Naveed et al., 2020). One such process is known as micro-
bially-induced carbonate precipitation (MICP). Its coun-
terpart, where enzymes are separated from the microbes for
use, is known as enzyme-induced carbonate precipitation
(EICP). Biocementation is rapidly expanding in the field
of environmental engineering and relevant applications of
this technology include soil stabilization, erosion control,
dust suppression, groundwater remediation, construc-
tion material fabrication and restoration, and toxic metal
immobilization (Mujah et al. 2017, Proudfoot et al. 2022,
Song et al., 2022). We are developing both enzymatic and
microbial approaches (EICP and MICP) for agglomerating
and controlling the strength and geotechnical stability of
a range of materials, including ore stockpiles and tailings.
Finally, several microbially-mediated processes, including
MICP and EICP, have the potential when applied to min-
ing materials to sequester CO2, therefore opening addi-
tional doors for meeting sustainability goals (Grayevsky et
al. 2023, Mirjafari et al. 2007, Ni et al. 2023, Okyey et al.,
2016).
EXPERIMENTAL
Bio-Solubilization
Allonnia is evaluating a range of bio-solvents for their abil-
ity to selectively solubilize gangue minerals, and remove
aluminum (Al), silica (SiO2), calcium (Ca), and magne-
sium (Mg) from the solids. The bio-solvents are composed
of microbial metabolites present within individual bacteria,
fungi, and/or microbial consortia that have shown poten-
tial for selective solubilization in natural and laboratory
conditions.
We have extended solubilization experiments across a
range of ore types, concentrates, tailings, and individual
minerals to understand baseline bio-solvent performance
and key operational parameters. The results presented in
this paper include an ore material that has been pulverized
to a P95 of 106 microns, a flotation concentrate and silica-
rich tailings with similar size distributions. Operational
parameter evaluations have included solid loading (5 to
30% solids by weight) and a range of temperatures (30 to
80°C) under well-stirred conditions.
The data presented in this paper were analyzed by a
commercial analytical laboratory using lithium borate
fusion disks measured on a wavelength dispersive X-ray flu-
orescence spectrometer (WD-XRF) and semi-quantitative
estimates of mineralogy were determined by X-ray diffrac-
tion (XRD) using the Rietveld refinement method. Both
methods included industry-standard QA/QC reporting
requirements.
BIO-CEMENTATION
Allonnia is evaluating promising microbes from our bio-
bank for MICP ability with a goal of also limiting urea
and Ca additions to create more economic, sustainable,
and environmentally friendly bio-cement formulations.
In addition, we are exploring applications for EICP and
the production of microbial enzymes at scale for mining
applications. As part of our experimental work, we have
been testing baseline reaction conditions and developing
cementation formulas and deployment strategies. We are
exploring key factors such as curing time, moisture content,
enzyme activity, temperature, and pressure on unconfined
compressive strength achieved through the biocementation
of mining materials. Further, we are testing the ability of
the ore and tailings bio-cement to withstand variable envi-
ronmental conditions (e.g., heat and moisture) and explor-
ing how different materials may inhibit these carbonation
reactions. These factors will determine the efficacy of the
calcite precipitation process for various mining applica-
tions including stockpile protection from the elements,
dust control, and liquefaction control for tailings and cargo
stabilization. We are testing additional biological additives
to reach target values for parameters such as strength and
moisture content.
CO2 SEQUESTRATION
Building from both our bio-solubilization and bio-cemen-
tation work, Allonnia is looking into the potential to use
microbial processes for carbon capture. While the ureolytic
pathway is the most commonly employed EICP/MICP
reaction, carbonic anhydrase catalyzes the reaction of CO2
and water into bicarbonate which can then react with cat-
ions such as Mg and Ca to create carbonates, thus remov-
ing CO2 from the atmosphere and storing it in a stable
form. Both concentrated CO2 and cations (e.g., Mg and
Ca) sources are abundant in the mining industry. In addi-
tion, we are exploring alternative carbon capture methods,
for example by inducing the complexation of microbially
produced metabolites with a range of solubilized gangue