Wastewater System for a Lightweight Aggregate
Manufacturing Plant
JOHN BALL, Assistant Professor
Department of Civil Engineering
Texas A&M University
College Station, Texas 77843
CHARLES A. STRYKER, Engineer
Wilson and Company, Engineers & Architects
Salina, Kansas 67401
INTRODUCTION
This case study presents the investigation and development of a wastewater handling
and disposal system for a new lightweight aggregate plant. The Superock, Inc. plant is
located about 60 miles south of Dallas near Streetman, Texas and can be characterized as a
high-capacity, fully automated facility.
Lightweight aggregate is produced at the plant using clay as the raw material. The
finished product is used in road construction and is particularly advantageous as aggregate
for lightweight concrete in long span bridges and high-rise structures (1). The specific weight
for the finished product ranges from 34 to 40 pounds per cubic foot compared to natural
aggregate at about 150 pounds per cubic foot. The savings in weight results in reductions in
handling and shipping costs in addition to reducing sizes in some structural members. This
is accomplished by reducing the dead load of high rise structures. The product has promise
for increased use in the future because it takes significantly less energy to transport to the
job site.
THE MANUFACTURING PROCESS
A block diagram of the manufacturing process is presented in Figure 1. Although
lightweight aggregate can be produced from shale, slag or fly ash, the Superock facility uses
a consolidated clay as the raw material. The plant was located near Streetman because the
clay strata that produces good lightweight material is reasonably close to the surface
requiring minimal overburden removal. Overburden is stored beside the quarry for use as
backfill.
After some 10 feet of overburden is removed, dynamite is used to break apart the
consolidated clay. The material is very hard and could be classified as a shale. Heavy
equipment loads and hauls the broken clay to the rock crushers. A series of three rock
crushers break the material into pieces no larger than one and one-half inch diameter.
Following the crushers, the material is conveyed to a series of screens to separate the clay
into various gradations prior to firing in a large rotary kiln.
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