I
n operation since 1955, SamQuarz is
the largest producer of high-quality
silica in South Africa. Its silica is used
primarily in the production of glass
and in the metallurgical smelting process
and meets 35% of the country's total annual
consumption.
The operation, which produces two key
products – high quality silica and chert –
comprises a large open pit and processing
plant. It supplies a number of blue-chip
companies in the glass manufacturing
industry and metallurgical sector.
There are other silica mines, but the
relative inferior quality of their silica,
available capacity and relative distant
location, render them unviable economic
alternatives to the downstream competitors
of the merging firms, observed the
Competition Commission in 2012 when the
quarry was the subject of a takeover bid.
How glass is made
The process for the manufacture of glass,
according to the PG Building Glass website,
is as follows:
• Raw material feed: silica sand, soda
ash, dolomite, limestone, sodium
sulphate and cullet (recycled glass)
are mixed together to form the raw
material batch.
BENEFICIATION
“Earliest archaeological evidence of glass manufacture
comes from ancient Egypt and Mesopotamia. Glass
vessels do not make their appearance until the late
sixteenth century BCE.”
molten glass floats along the surface of
molten tin. All irregularities are melted
out of the ribbon, to give the glass a
flat, parallel surface.
• Annealing lehr: the glass is annealed
and gradually cooled to about 200°C,
to relieve stresses in the glass and
prevent splitting and breaking in the
cutting phase.
• On-line cutting: the ribbon moves to
the ‘cold end’ of the line where it is
washed and automatically cut, as it
travels along the rollers.
• Stacking and offloading: automatic
stackers offload the glass sheets.
The glass is then warehoused for
distribution.
• Distribution: the glass is distributed
throughout South Africa and exported
into regional and overseas markets.
A history lesson
• Float bath: a continuous ribbon of Though glass is today one of the most
• Furnace: the batch is fed into the
furnace and melted at a temperature of
about 1 500°C.
common building materials for windows,
as well as many ornamental objects and
computer communications, its initial use by
our earliest ancestors was as a sharp weapon
and useful tool.
Earliest archaeological evidence of
glass manufacture comes from ancient
Egypt and Mesopotamia. Glass vessels do
not make their appearance until the late
sixteenth century BCE. Within a short
time Mesopotamian glass products and
the knowledge of how to make them were
exported to other major centres of Late
Bronze Age civilisation, the most important
of which was Egypt.
The discovery of glass-making enabled
man to exploit a material that could be
used for countless different purposes and in
every imaginable form. The appeal of glass
throughout antiquity was without doubt
based on its practical virtues, but it may also
be linked to the fact that it is an artificial,
man-made substance. In the Roman period
the invention of glass-blowing brought
The making of flat glass is highly mechanised.
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QUARRY SA | NOVEMBER/DECEMBER 2018_33