CASE STUDY: Foundry Sand as an Alternative Raw Material in the Manufacturing
of Cement
Geocycle
Mason
Geocycle US, based in Dundee,
Michigan, is a subsidiary of Holcim (US)
Inc. focused on offering customers
solutions to their waste management
needs by utilizing the co-processing
capabilities of cement manufacturing.
Co-processing is the substitution of
fossil fuels and naturally occurring
materials with waste in a manufacturing
process. The recoverable materials are
diverted from other disposal options
such as landfills and incinerators, which
preserves natural resources for future
generations.
Holcim is one of the largest suppliers of
Portland cement and related mineral
components in the United States.
Founded in 1908, Holcim's Mason City
plant has been continuously producing
cement for 100 years. Portland cement
is made from four elements: silica,
aluminum, iron, and calcium. The
cement manufactured at Mason City is
transported to several regional states to
be used as a main ingredient in
concrete.
The site receives about 75,000 tons per
year of foundry sand, which replaces
naturally occurring, virgin silica in the
cement production process. Geocycle
US currently receives the spent foundry
sand from eight regional foundries
located in Iowa, Minnesota, Wisconsin,
and Illinois, with over half of the foundry
sand coming from Grede Foundries, Inc.
in St. Cloud, Minnesota. In most cases,
Geocycle US and the foundry share the
cost of transporting the sand from the
foundry's location to the Mason City
plant.
(Holcim)
Iowa
Figure 1. Unprocessed core pile.
Depending on the generator, Geocycle
US receives the sand in one of two
forms: spent dry sand or sand cores.
The dry sand may immediately be used
in the production of cement, but the core
sand contains hard chunks of solid sand
that must be ground, screened, and
processed before use. What makes the
Mason City site unique is not only the
amount of foundry sand it receives for
co-processing, but also the site's ability
to crush and process sand cores on site.
Geocycle US at Mason City allows
some small foundries the opportunity to
re-use their foundry sand, as these
foundries may not have the resources to
crush and screen their cores before
sending them off for co-processing.
core sand.

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Holcim's use of spent foundry sand in
cement production results in several
mutual benefits. The foundries avoid
landfilling their spent foundry sands, and
the Mason City plant reduces the use of
a naturally occurring material like virgin
sand. Also, the cement manufactured
with foundry sand is a sustainable
product that meets applicable quality
standards and contributes to
environmentally friendly applications. In
addition, due to the use of recycled sand
and other alternative raw materials in its
cement products, the Mason City plant
has a favorable relationship with the
Iowa Division of Solid Waste
Management and various other
stakeholders.
Both Geocycle US and its source
foundries are pleased with their
relationship because it results in
sustainable development gains for both
parties. Several other foundries have
expressed interest in working with
Geocycle US and Holcim's Mason City
plant in the near future.
Figure 3. Machine that dries crushed and
screened core sand.

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Case Study: Geocycle US: Foundry Sand as an Alternative Raw Material in the
Manufacturing of Cement
Personnel
End User: Geocycle US (Holcim US)
Foundry: Grede Foundries, Inc.
Site
Recycling Location: Mason City, IA
Site Description: Holcim's Mason City
plant uses spent sand from several
foundries for its cement production
process. The cement is used as a main
ingredient in concrete.
Materials Utilized
75,000 tons per year of spent foundry sand
in the form of dry sand or sand cores.
Project Costs and Benefits
Costs Include:
•	Transportation of the sand from
foundries to the Mason City plant.
•	Geocycle US conducts chemical
and physical analysis on the sand.
•	Geocycle US crushes and
processes sand cores on site.
Benefits Include:
•	The foundries forgo the cost to
landfill spent sand.
•	The Mason City plant avoids the
use of naturally occurring materials
like virgin sand.
•	Cement made with recycled
foundry sand is a viable option to
reduce the environmental footprint
for both parties.
•	Cement manufactured with foundry
sand is a sustainable product that
meets applicable quality
requirements and contributes to
environmentally friendly
applications.
•	The Mason City plant has a
favorable relationship with
environmental regulators and
stakeholders.

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