Recycling - its a sign
of the times. From paper and plastic products to electronic
wastes and metals, the recycling movement is growing. There is
one company that has now brought this concept to the industrial
minerals field. Alexander Mill Services International Inc.
(AMSI), based in Harmony, Pennsylvania, USA has been supplying
the foundry, refractory and special minerals industries with
reclaimed products since 2005.
AMSIs involvement with
chromite reclamation began in July 2003, when Tom Vlajkovich, a
broker for American Waste Management Services, contacted the
company about its interest in the reclamation of a hazardous
waste landfill in Ohio.
He posed the question; can
you reclaim chromite sand from silica sand, John
Alexander III, president of AMSI, told IM.
Yes I said, yes I can. I did not want to miss the
opportunity, and although I was not even vaguely aware of what
chromite sand was at the time, I was certain that given our
past experience, it would be easy. Little did I know how wrong
I was about to be.
From 1967 until 1994, the Ohio
landfill site was utilised as a dumping facility for a large
steel foundrys waste sand, steel scrap, slag and iron
oxides, as well as sludge from its sand washing process. The
sludge was generated as a slurry from washing sand that used a
bentonite clay binder in the foundrys green
sand system. Bentonite clay has the capability to hold
several times its dry mass in moisture, a property which makes
it one of the most difficult materials to process.
Core room chromite
Original estimates placed the landfill volume at over 600,000
tonnes with chromite estimated at 30% and the bentonite clay
sludge at 20%. Also included in the landfill was electric arc
furnace (EAF) dust. The EAF dust, due to its potentially high
concentrations of barium, cadmium and lead, caused the landfill
to be listed as a hazardous waste site. Working in conjunction
with the Ohio Environmental Protection Agency or OEPA, the
focus of the project was to process the material in the
landfill with the intention of reclaiming the valuable chromite
sand for reuse at the foundry, while testing the process
outflow to guarantee that no harmful constituents were present.
The project was scheduled for completion over a seven-year
In preparation, AMSI was provided
with chemical analytical and sieve sizing information outlining
the desired limits acceptable in the reclaimed chromite
product. Utilising this information as a starting point, AMSI
contacted equipment specialists to explore the possibility of
creating a system capable of handling the material. Mc Lanahan
Corp., based in Hollidaysburg, PA, was chosen for its expertise
in wet density separation and Eriez Magnetics, in Erie, PA for
its specialised magnet experience.
In gaining a better understanding
of the foundry material, a more clear vision of how to take
advantage of its inherent properties was gathered. The most
important aspect of this observation was that all of the sand
products arrived at the foundry as a specification product. It
was AMSIs job to remove the residual impurities,
including the binders, slags and oxides, from this material and
bring it back to as close to specification as possible.
AMSI initially focused on the obvious density and magnetic
separation differences between the chromite, silica and other
highly and mildly magnetic materials. Laboratory tests showed
very promising results, and the decision was made to move
forward with the project. The facility became operational in
To say that we were plagued
with problems from the onset would be an understatement. It was
immediately realised that the information that was provided to
us regarding the landfill values was inaccurate. New core
borings taken at the facility after we had begun operations
showed that the sludge content was higher than 50% as opposed
to the 20% that was documented, Alexander explained.
The chromite content was also
dramatically different at roughly 6% compared to the listed
30%, while the bentonite caused serious problems from a
processing perspective. Due to the ultrafine nature of the
material, a specialised blend of sulphuric acid, coagulants and
polymers had to be developed in order to solidify the
AMSI worked with a number of
chemical companies in the USA in an effort to solve this
problem. The site currently uses a proprietary flocculent,
supplied by Chemtreat, which was developed specifically for
The bentonite overwhelmed the
dewatering equipment which had been designed for lower output.
Without the appropriate equipment, it appeared that the project
would fail prior to even becoming fully operational. It was
only with the cooperation of the OEPA that AMSI was allowed to
create large holding ponds to store the sludge on site, solving
The problems that we had
encountered with the material up to this point had severely
hampered our ability to create the product quality that we had
originally intended and we had to approach our customer with
the concept of utilising a lower grade chrome product,
As the foundry that had generated
the material had intended to utilise the chromite as blend sand
in its green sand system, the product quality was acceptable
for this process and the foundry became the first, and for a
while, only customer of AMSIs reclaimed sand product. The
company was joined shortly thereafter by a sister company that
had similar sand needs.
As production increased, AMSI
needed to expand its sales horizons. Initial attempts to market
the product further into the foundry industry had failed, due
not only to the higher than specification silica content, but
more importantly, to the high acid demand value (ADV). As the
original chemical analysis report that was provided did not
include an ADV test, AMSI did not make this a part of its
testing protocol and therefore did not have the necessary
separation technologies in place to tackle this issue. This
oversight had created a significant problem in attempting to
manufacture a chromite product that could be used
interchangeably with new material.
In 2007, AMSI started to evaluate
secondary technologies that could remove the mildly magnetic/
high calcium slag materials that were creating the ADV issues.
It was determined that although the slag and chrome had
equivalent magnetic attraction properties, they had different
specific gravities. To this end, AMSI had determined that air
separation technologies would not only solve this problem, but
would best fit the profile of its facility.
Alexander and the companys
plant manager, Mark Sowers, discussed Oliver Manufacturing Co.
separation equipment in great detail. At the time, most people
equated Oliver machines with agricultural separation.
More than a few people
thought that we were a little crazy for wanting to use Oliver
machines to purify chromite. Regardless, Mark and I made the
trip to Colorado and spent two days working with Jim Thomas,
design engineer for Oliver, in proving that this concept could
work, revealed Alexander.
The company installed Oliver air
bed separators in 2008. With these units in place, AMSI was
capable of producing chromite sand that met much more stringent
Upon review of available chromite
specifications, AMSI chose to follow the Steel Founders
Society of America, Tentative Specification for Chromite Sand
and Flour (SFSA 16-T67) issued in 1967 (Table 1).
AMSI is producing a product that
easily meets these specifications. The company has continued to
strive to improve product quality, and has made recent
improvements in its processing technology. These changes were
made in answer to a problem discovered during extensive
research, wherein the chromite sand that has been in contact
with the highest heat from the steelmaking process goes through
a slight conversion phase and exhibits characteristics that are
out of specification with new chromite.
AMSIs processing changes have
given it the ability to separate this spent
material, with successful results - an overall lowering of
the silica content and an increase in the chrome units.
It is often asked if AMSI chromite
is a realistic alternative to new chromite: AMSI currently has
14 customers in the US foundries and refractory markets, with
more companies in various phases of testing its product, that
have made the chromite a critical part of their supply
The companys goal is to continue to create reclaimed
chrome products that meet the needs of the foundry, refractory
and chemical industries. In order to accomplish this goal, AMSI
is researching other avenues to gather waste chrome products.
It monitors and documents foundry landfills
opportunities - as this is the core of the companys
new business model - and is also in discussions with
operating foundries on the installation of in-house separation
systems that can strip the chrome and oxides from the silica
AMSI has also worked with core
manufacturing facilities and foundries to collect scrap cores
for reuse, and continues to evaluate reuse potential for
refractory wastes and other chrome bearing materials.
We see every pound of
chromite that comes into these facilities as a resource that
can be used many times over, stretching the life cycle of this
material almost indefinitely, Alexander commented.
In each of the scenarios in which
reclamation is an alternative, it is critical to evaluate all
possible revenue sources that are a part of the total. Foundry
landfills can contain ferrous and non-ferrous scrap, iron
oxide, steel shot, carbon electrodes, zircon and chromite
sands. With the increasing interest in reclaimed proppant
(fracturing) sands used in the oil and natural gas industry, it
important to note that the largest constituent of the landfill
itself, the silica sand, could possibly be one of the highest
Although each landfill would
require specialised separation technologies designed to
capitalise on its own inherent properties, many of these pieces
of processing equipment can be utilised in different
combinations as needed on different projects. This
compartmentalised approach is fundamental to keeping
installation, as well as investment, costs in line.
AMSI has done extensive research on
many foundry properties and found that in a typical foundry
landfill operation, processing 10,000 tpm could yield the
following results as shown in Table 3.
This plant capacity is in keeping
with AMSIs Ohio facility which operates at 50 tph. It is
not hard to visualise how a larger plant, such as a 200 tph
operation, could significantly shift the dynamics of this
model. Processing 40,000 tpm could yield the following results
as shown in Table 4.
As Table 4 shows, expanding on this
concept changes the dynamics quickly. Although it would cost
roughly twice as much to build a 200 tph plant versus a 50 tph
plant, revenue would quadruple, while operating costs, as a
percentage of revenue, would be reduced by more than half.
In many of these landfill
scenarios, the foundry is under a state or federal order to
remove some or all of the sand from its facility. In these
cases it may be possible to negotiate a processing fee that
would cover many up-front costs, once again, lowering overall
costs and boosting potential profit.
Because chromite is not AMSIs
only product, the pricing of the material is less contingent
upon outside factors such as availability or transportation
costs, but more in line with current chromite pricing. In
recognition of the fact that the company offers a reclaimed
product, AMSI continues to sell this material for lower than
Foundry landfill site in Ohio, USA
Hub and spoke concept
In an effort to more efficiently and cost effectively reclaim
materials, AMSI is in the process of building smaller scale,
highly efficient scalping plants that can separate
the valuable chromite, as well as other reclaimable products,
from the sand. Once these materials are removed, they can be
transported to a hub facility, similar to the operation in
Ohio, where they can undergo secondary processing, packaging
and shipping. In this manner, numerous small jobs can be
operating in a set geographic area while keeping large
investment overhead and transportation costs to a minimum.
AMSI continues to push the
boundaries of reclamation technologies. The company is the
first of its kind to sell a recycled chromite product, the
first to sell a recycled iron oxide substitute and the first
company to have a recycled silica product approved by the
American Petroleum Institute. In the course of this work AMSI
continues to diminish unsightly and potentially dangerous
landfills while saving companies money on much-needed
Contributor: John Alexander III, president, Alexander
Mill Services International Inc., Pennsylvania, USA.
Spotlight on Alexander Mill
Founded in 1981 by John S. Alexander Jr., AMSI provides
recycling services to steel mills and foundries. These services
include the removal of slag from the steelmaking process, as
well as the reclamation of ferrous and non-ferrous metals from
the waste slags and sands that have been generated by these
facilities. The steel products are recycled back into the
facilities melting process, while the slag and sand
products are used in alternative aggregate applications.
AMSI has performed these services
throughout the USA at 17 operations, including Nucor Steel,
Structural Metals, and Florida Steel and throughout Europe at
13 operations, including Huta Ostrowiec in Poland, COST in
Romania, Halyvourgia Thessalias in Greece and Siderugia
Nacional Empresa in Portugal.