Saiccor - The First 50 Years 5.8 MB - Sappi

The First Fifty Years
Design work for chlorine dioxide bleaching (including No 8 filter)
started in November 1962, orders were placed from December 1962,
plant erection started in May 1963 and the plant was commissioned
in December 1963� No 1 filter in bleaching was replaced with a Kamyr
M57 unit almost twice the size in May 1965, after first installing a
temporary filter to enable No 1 to be taken out� In November 1965
No 4A filter was commissioned, which effectively doubled the
washing capacity after the chlorine dioxide stage�
A second Rauma pressure washer was ordered in June 1964 and
commissioned in August 1965� In December 1964 a fourth thickener
was ordered for second screening, which was started up in June 1965�
With all the new plant and equipment being installed, power
consumption increased significantly, making it prudent to increase
Saiccor’s power generation capacity� The foundations for No 3
turbogenerator started in April 1964� This was a 6,5 MW Allen
machine that doubled the total generating capacity� The machine
was started in March 1965�
Sheet pulp quality did not change over the period 1960-1965�
Blockage constants (KWs) averaged around 15, although often ranging
above the Courtaulds limit of 20� Calciums were high, with monthly
averages from 450 to 650 ppm summer to winter, while silicas
averaged around 50 ppm� Until flock pulp went through second
screening (June 1962) KW values averaged 30 and silica 270 ppm�
After June 1962 these values dropped to 19 and 60 respectively�
Courtaulds were not entirely happy with Saiccor’s pulp quality,
particularly the high calcium levels� Fred Aldred, John More, and
Malcolm Simpson from Courtaulds paid a number of visits to Saiccor
to investigate what could be done to improve calciums, but nothing
proved successful� Copper numbers (about 1,6) and resin (about 0,35
per cent) were considerably higher than today’s levels of about 1,2
and 0,1 per cent�
Various timbers were tried� Wattle was first used in 1957, but the
KW was 100� Wattle usage continued over the years up to 20 per cent
of the furnish, but its pulp had high KW values until it was cooked
separately in high pressure digesters (from 1970), then the percentage
wattle was increased reaching a peak of 40 per cent in the late 1970s�
The first trial using pine was done in November 1959, and was
successful� For a period in 1962 pine was blended up to 5 per cent
with saligna, producing satisfactory pulp� Casuarina was tried but
proved unsuitable�
The first 2 500 t of high alpha pulp for the American market
(Mobile) was made in November 1961� A second lot was made in
January 1962� Mobile received 94 alpha for a few years but then it
was decided 94 alpha was not an economic proposition for Courtaulds
and Saiccor combined� A further 94 alpha trial was conducted in the
late 1970s, but was only made commercially from 1996�
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