Tests were carried out in 1998 in a 180 t / 24 h soft wheat mill in Poznan (western Poland). Three pairs of self-matting rolls were installed in roller mills, which had both pairs of rolls working on the same passage. The trials were therefore made on C2, C3 and C5. On one side standard sandblasted rolls were installed (hardness 430-470 HB). On the other side the SM (self-matting) rolls were installed. During the trials the basic parameters of the mill, the wheat as well as the products being obtained were unchanged. Trials were continued and data collected over a period of over 3 weeks.
RESULTS: 1. Intensification of the milling process.
With a same gap setting on both sides the SM rolls were producing slightly more flour. Taking the B1 value as 100 % the increases obtain was C2-2.1 %, C3-1.8%, and C5-1.3 %. In comparison with the normal rolls the increased yield was 14%, 18 % and 23 % respectively. In the case of the main fraction being produced –200 micron – the quantities obtained using the SM rolls were higher by 30%, 34 % and 37 % respectively. This clearly shows that the milling process has been intensified. The smaller the size of the particles being milled and the greater the proportion of bran they contain – the higher effectiveness of the SM rolls. The intensification of the milling process meant that one of two changes could be made to the mill flows in existing mills.- Milling results could be maintained at higher throughputs ( more product being fed onto the same length of rolls )- fewer passages would be needed to obtain high extractions of flourIn both cases the end result should be an overall increase of capacity of existing mills. The results obtained in the mill in Poznan confirmed this. The capacity and extraction levels were monitored over a period of 2 years (1997 and 1998). In 1997 traditional rolls on compression passages were used. In February 1998 all the traditional smooth rolls were replaced with SM rolls. The quality of grain being processed during the entire period was fairly uniform. The milling process, the equipment installed and the market situation were also similar during both periods. The introduction of SM rolls was the only major change made in the mill in 1998. Results obtained during the entire 1998 showed that the extraction of flour was 2.42 % higher then in 1997 and the capacity of the mill increased from 180 t / 24 h to 200 t / 24 h. Even if we assume that some of the increase in extraction and capacity were a result of other factors, there is little doubt that the introduction of the SM rolls produced a noticeable increase of both parameters.
2. Improved flour quality.
The flour produced has improved. The following results were obtained.The level of sedimentation (quality of gluten) rose by 3-5 pointsWater absorption of flour increased by 0.8-1.4 %.The activity of the alpha – amylase was unchanged.Tests made in 1999 in Canada showed that the level of protein increased by ca 0,25 % and base flours were noticeable less speckled and lighter in colour. In the tests in Poznan despite the 10 % increase in the capacity of the mill the ash content is practically unchanged. In Canada tests showed that with a constant capacity of the mill the ash contents fell by 0.16 %.
3. Lower consumption of electric energy.
The energy consumption of the SM rolls in comparison with standard rolls was lower by 2.5% -5.7 %. In general the smaller the particle size of the product being milled the lower the energy savings.
4. Lower milling temperature.
One of the characteristics of the smooth rolls working on the compression passages is the relatively high working temperature of the rolls. With the SM rolls the working temperature of the rolls was lower by 3.6-5.7 degrees C (6-10 degrees F).
Which in turn lowered the temperature of the product by 2.5-3.4 degrees C (4-6 degrees F).
5. Lower maintenance cost.
For the past two years the rolls installed in 1998 have not required any maintenance as they are still maintaining a “sandblast” finish (May 2000). The results being obtained have also not shown any noticeable deterioration.
During the last four years 1999 – 2003 over 2000 Prillwitz SM rolls of various lengths and diameters. have been installed in mills in Poland, Germany, The Netherlands, Italy, United Kingdom, USA, Canada , Argentina, Chile, Peru, Colombia, India, Bangladesh the Philippines Up till now the feedback we have received from all these mills confirm the benefits of the SM rolls in the milling process and their superiority over the conventional sand blasted milling rolls.
Prillwitz is carrying out further work on the development of the SM rolls. Thanks to the co-operation of Polish metallurgical institutes and the Central Laboratory of Grain Processing in Poznan and in Warsaw we are also learning more about the potential benefits of this product. Prillwitz commitment to quality and technological improvment is once again stressed when it comes to choose those products it comercialize under representation.
PRILLWITZ Ostrów Wielkopolski S.A. is one of the biggest European manufacturers and suppliers of cast iron rolls. Based on more than 120 years experience, Prillwitz´s rolls incorporate the most advanced technologies, thereby achieving an impassable … Read more