Chemical Engineering January 2022 - 24

perform a commercial scale test involving
production of typically 10-20
tons of catalyst. After just one wellplanned
test production at Topsoe's
plant in Bayport, Tex., the company
decided to commercialize this new
high-performing catalyst.
Topsoe manufactures its own
pseudo-böhmite, which is the raw
material for the alumina support. This
allows full control of the entire manufacturing
process and coupled with
tight quality control in manufacturing,
it enables Topsoe to achieve the desired
catalyst performance.
Since it was launched in 2019,
Topsoe has achieved ten sales, with
several already installed and performing
excellently, according to the
company. The TK-6001 HySwell has
delivered up to an impressive 17°C
improvement compared to the previous
catalyst in a commercial unit.
HONOR ACHIEVEMENT
BQE Water
Selen-IX™ process
Responding to growing environmental
issues associated with selenium
pollution in the mining industry, BQE
Water developed the Selen-IX technology
as an industry-specific solution
to manage the selenate form of
selenium in wastewater. While selenium
can be present in many chemical
forms, selenate is the most prevalent
and most difficult to remove.
Commercialized in 2020, Selen-IX
represents a disruption in selenate
treatment dominated by biological
reduction systems by offering capabilities
other systems cannot. Specifically,
Selen-IX can:
* Meet end-of-pipe selenium limits
<2 ppb without reliance on dilution
* Produce stable inorganic solid residue
with off-take potential
* Remove selenate " selectively " from
wastewater containing a cocktail of
ions without adding any chemical
reagent or constituent to the water
that was not previously present
* Remove selenate without transforming
any part of it into a more bioavailable
form of selenium such as organo-selenium
or selenocyanate
* Adjust rapidly to fluctuations in
feed water flow and composition
* Operate intermittently with instant
ramp up/down regardless of feed
24
Development
timeline.
Development of Selen-IX
began in 2012 at a bench
scale
in BQE Water's
FIGURE 2. Shown here are the ion-exchange columns of the first
industrial-scale Selen-IX plant
water temperatures
The Selen-IX process. The novelty
underlying Selen-IX is the unique integration
of ion exchange (IX) and
electro-reduction (ERC) to remove
selenate to levels well below North
American selenium regulations that
currently range from 1 to 10 parts per
billion (ppb), while also eliminating the
generation of a liquid brine waste that
is associated with conventional IX and
membrane treatments. A U.S. patent
for Selen-IX was issued in 2018.
Selen-IX is comprised of two main
unit processes. In the IX part of
Selen-IX, non-selective strong base
anion resins are used to selectively
capture selenate from influent to produce
regulatory compliant effluent
for discharge into the environment.
Once saturated with selenium, brine
is used to elute selenium from the
resin to enable its re-use in subsequent
cycles, similar to conventional
IX. A compelling feature of Selen-IX
is the recycling of brine through ERC
treatment. Recycling eliminates liquid
waste typical of conventional IX
and imparts selectivity to resins that
are otherwise non-selective.
The purpose of the ERC process
is to remove selenate from the brine
down to levels enabling the brine to
be re-used in the IX and to fix the selenium
into stable non-toxic solids.
At the heart of the ERC is an electrochemical
cell that features a sacrificial
iron anode similar to electrocoagulation
(EC). However, unlike
conventional EC that releases iron
into solution to co-precipitate metals
and metalloids without changing
their valence, the ERC changes the
selenium oxidation state from +6 to
0 to create a solid matrix that gives
stability to Selen-IX solids with minimal
risk of selenium re-release.
BQE Water
laboratory in Vancouver,
Canada. Promising results
garnered the attention
of a coal producer. In
2013 a mobile pilot plant
was constructed and the
first pilot campaign to remove
selenate from coal
process waters was carried
out. This project successfully
achieved the objective of producing
effluent containing <5 ppb selenium.
Further bench-scale development
took place in 2014, followed by a second
pilot campaign for a gold project
in development. Selenium contamination
of water was recognized as a
key issue in the permitting of the project.
Results of the pilot demonstrated
selenium removal to <1 ppb and enabled
the mine owner to satisfy an integral
condition of their environmental
assessment certificate.
A third and final pilot was completed
at the end of 2015 for a copper
and gold project. As part of the
permitting requirements, Selen-IX
was piloted to demonstrate the removal
of selenium from mine water
to <1 ppb. The results were in compliance
with the site-specific regulations
and enabled the mine owner to
secure the necessary environmental
permits to advance their project.
Throughout the many bench- and
pilot-scale testing campaigns, progressively
better process efficiencies
were achieved which had the positive
impact of reducing capital and operating
costs for Selen-IX while producing
effluent containing <1 ppb selenium.
Inaugural Selen-IX Plant. After the
positive results from their pilot and
the success of the industrial demonstration
project, the copper and gold
client made the decision to proceed
with a full-scale Selen-IX plant (Figure
2). Located in Northern British Columbia,
the capabilities of Selen-IX are
perfectly suited for the requirements
and conditions of this remote mine
site where selenate is the main contaminant
of concern.
Specifically,
provincial
CHEMICAL ENGINEERING WWW.CHEMENGONLINE.COM
regulators
applied a <2 ppb end-of-pipe discharge
limit for selenium. Due to its
JANUARY 2022
http://WWW.CHEMENGONLINE.COM
Chemical Engineering January 2022

Table of Contents for the Digital Edition of Chemical Engineering January 2022
