Chemical Engineering March 2017 - 10

A new filter mesh with reduced erosion - by design
P
orometric mesh is a new
weave mesh designed by
GKD-USA, Inc. (Cambridge,
Md.; www.gkdusa.com) using
computational fluid dynamics (CFD)
simulations (photo), in a study aimed at
reducing erosion and abrasion caused
by sand in oil-and-gas pipelines.
Porometric mesh has a very open, 3-D
mesh construction that, while maintaining
a constant volumetric flowrate,
reduces local pore velocity by
up to 40% compared to conventional
filtration meshes, with throughput increasing
by a similar factor, says the
company. With a pore size of 150 µm,
this new mesh type achieves an air
Batch or continuous?
This methodology can help making the decision
S
T
10
o far, there is no high-level
evaluation that gives a simple
guideline on the benefits
and feasibility of converting a
batch to a continuous process. Now
a group from the Agency for Science,
Technology and Research (A*STAR;
Singapore; www.ices.a-star.edu.sg)
has developed a practical methodology
that enables a process-development
team to evaluate its existing
batch process holistically. This can be
especially valuable for fine chemicals
and pharmaceuticals industries that
might want to look into the possibility
of achieving step-change improvements
in an existing process to address
cost and regulatory concerns.
The group's proposed methodology
consists of three stages: initial screening,
extended evaluation and process
execution. The initial screening aims
to uncover key business requirements
and potential pitfalls, such as sticky reagents,
with simple yes/no/maybe evaluations.
Successful candidates are then
broken down into flowchart analysis that
identifies issues such as possible equipment
and control schemes. If the analysis
makes economic sense, a final stage
of process execution is put in place.
The A*STAR group has applied its
methodology to three reactions with
fairly complex molecules that have
Heap leaching targets nickel from laterite
he NiWest Nickel Laterite Project
located at Murrin Murrin in
the North Eastern Goldfields
of Western Australia, has the
potential to become a significant
long-term, low-cost nickel producer
through the development of heap
leaching. The project is 100% owned
by GME Resources Ltd. (Fremantle;
www.gmeresources.com.au) through
its subsidiary NiWest Ltd.
Total metal content of more than
1,000,000 metric tons of nickel has
been defined by extensive drilling
programs. While most laterites have
a high iron content of about 40%,
Murrin Murrin has an iron content of
about 18%.
The project will be a heap leaching
operation combined with a processing
plant utilizing direct solvent
extraction and electrowinning to upgrade
purified nickel solutions from
the heap leach to produce LME (London
Metal Exchange) nickel cathode.
GME Resources has also developed
and patented a regeneration and laterite-agglomeration
technology that
will enable all ore types to become
heap leachable.
Multistage leaching of the ore will
produce LME cathode nickel as well
as a cobalt carbonate precipitate
after being exposed to acid regeneration,
the removal of iron, neutralization
and solvent extraction before
finishing
up
with
electrowinning.
The heap-leach solution circuit will
include the removal of iron and the
acid-regeneration process through
its use of a dynamic on-off pad system
where the spent ore and residue
will be removed and discarded
into a pit.
A scoping study highlighted that the
proposed processing route offers a
significantly lower capital cost over the
alternative and more complex highpressure
acid-leach process. The NiWest
processing plant will be capable
of producing 540 m.t./yr of cobalt carbonate
and 14,000 m.t./yr of nickel
cathode. The mine life will be longer
than 20 years.
CHEMICAL ENGINEERING WWW.CHEMENGONLINE.COM
MARCH 2017
been operated in the group's laboratories
at both batch and continuous
mode. The reactions are: synthesis of
-hydroxyester via the Reformatsky
route; synthesis of 4,D-erythronolactone;
and phase-transfer catalysis of
O-alkylation of 3-phenyl-10-propanol.
Liquid-phase
reactions
that
proceed
quickly and release or absorb
large quantities of energy proved to
be particularly favorable for continuous
processing. For example, the
group showed that the Reformatsky
reaction - an organo-zinc-catalyzed
reaction that frequently overheats with
batch processing - could profit from
a continuous approach.
permeability of 4,800 L/m2/s at a
pressure of 200 Pa. In contrast,
a plain weave with the same
pore size has a permeability level
of only 2,500 L/m2/s at 200 Pa.
So, at the same volumetric flowrate,
the more-open structure
of the new mesh almost halves
the local pore velocity. The lower
maximum pore velocity results in
lower wear of the filter material
from particles.
Currently, the company offers
Porometric mesh with a geometric
pore opening of 150 and 175
µm, and the mesh is now undergoing
practical tests that are confirming
GKD
the values calculated in the simulation.
The company is also working on
a Porometric mesh family with pore
sizes between 20 and 750 µm.
http://www.gkdusa.com http://www.ices.a-star.edu.sg http://www.gmeresources.com.au http://WWW.CHEMENGONLINE.COM
Chemical Engineering March 2017

Table of Contents for the Digital Edition of Chemical Engineering March 2017
