About us
Privacy Policy

What you should know about our „screening units“!
More than 20 years ago we were just as good or bad in screening as our competitors.
Since 26.09.1999 – the day of the patent application – we just happen to be better.
Our patented “screening device for bulk materials” is different from sieving devices
built by competitors, because the diameter of a screen-star is calculated precisely
according to the desired particle size of the material that is to be sieved so that
oversize particles are “eliminated” from the finer fraction. This is achieved by using
maximum acceleration at the lowest expenditure of energy and minimum
abrasion (see below: Test the screen-star).

As a principle we sieve between the screen-stars and not on or between the teeth or
fingers of a screen-star. The width of a screen-star must always be smaller than the size
of the particles to be sieved. Whoever explains in others terms is not talking about
defined “sieving” within small tolerances.

The material screen-stars are made of:
Our screen-star can be made of plastic, steel, wear-resistant Hardox 400, stainless
steel or acid-proof (acid- resistant) VA. We do not use one screen-star type for
all materials, but screen-stars which are specific to the material in diameter,
width and quality.

Crossed screen-stars:
If coiling of certain constituents or blockage caused by sticky materials such as
adhesive soils or composts are to be expected, then – according to a certain
system – we insert screen-stars with 4 teeth crossed to the right and 4
crossed to the left; these are self-cleaning. We screen with little coiling
and blocking. It is not possible to screen without any coiling or blocking,
because any screening-device can block if dosing of the material is improper.

The sieving speed is frequency regulated and adjusted to suit the structure,
composition and dosage rate of the material in such a way that no oversize
material is among the screened fraction.

Re-starting the screening unit:
Our patented screen-stars enable re-starting depend on material of loaded
screening units after an emergency shut-off or power failure etc. without
any problem.

Particle sizes that can be sieved and sizes of screening units:
We can screen characterized and defined fractions from 0-4 mm up to 500 mm.
To date we have built approx. 940 m of stationary or mobile screening lines
for sizing materials ranging from 0-4, 0-5, 0-6, 0-7, 0-8, 0-10, 0-12, 0-15, 0-20 etc.
up to 500 mm using screening widths ranging from 500, 750 1.000 to 1.250 mm.
Our smallest screening line is 3 m long, our longest has a length of 53 m.
To build a one-level screening line for screening 5 or 10 different particle
sizes is absolutely no problem.

Foam materials:
We can screen particle sizes of 0-4 mm out of shredded foam materials
having a bulk density of only 12 kg/m³. In the automobile industry, due
to reasons of weight, particles sized 0-4 mm are not used for manufacturing arm-
and headrests. Other screening techniques cannot do the job, because they
are not able to accelerate particles that are almost weightless.

Composted material – A call for tenders in Europe:
As a result of a Europe-wide call for tenders for a screening line for a composting
plant in Lahti, Finland, the award of the contract was given to our company with
the patented screening system. There is simply no better system available.
For screening such “aggressive” compost we installed crossed and acid proof screen-stars.

Blast-furnace slag:    (municipal solid waste incinerator bottom ash)
In Italy we are currently constructing a screening unit for sieving out the 0-8 mm
sized particles contained in the blast-furnace slag from different furnaces, which
has a bulk density of 1.500 kg/m³. The 0-8 mm fraction is recycled by the cement
industry and another particle fraction is used in road construction.

Other examples:
When the rubber parts of old tyres are pared off for re-treading, in particular,
we don’t have any problems with the long rubber parts in the rough dust.

The screening of shredded tree roots for use in bio-filter units is of no problem at all.

It is no joke: we screen the “Ladybirds” out of spinach leaves.

The solution to your screening problems:
Whatever material with a bulk density from 12 to 1.800 kg/m³ you intend to screen,
we have the solution with a stationary or mobile screening unit. Please give us a brief
description of the material and, if possible, state the bulk density, the maximum
size in mm, the maximum weight of the oversize fraction in kg, the preferred capacity in m³/h and the particle size range of the fraction or fractions to be sieved in mm.

Before we make you an offer, we shall test-screen a minimum of 150 litres of your material
made available to us by using our FRAKTIOMETER unit (see description).
You will then receive the test results in fraction percentages, the actually
sieved portions of the test sample and the bulk density in kg/m³ determined
according to the European Standard for the determination of the quantity,
EN 12580, (see VOLUMETER) for your inspection and own judgement.
In the end no one wants to buy a pig in a poke. You need to know beforehand
what the percentage of each fraction of your bulk material is, which you can
use and market.

By proceeding as described above we get a better feeling and  understanding
for the specific composition and behaviour of your bulk material on the screening
line. Based on the portions of each fraction we can determine the length of each
screening line in relation to the narrow tolerances you specify for each fraction.
We also determine the most suitable diameter and thickness of the screen-star –
always being smaller in diameter than the sieved fraction –  made of the most
proper type of material. There is hardly any other company that does all of this to
guarantee the performance  (output) of a screening unit.

Test the screen-star:
Please test various screen-stars by downloading our demo-film (3,4 MB). Best print
and study the text in advance and then start the screen-star test. Doing so you
can get to know our patented screen-star which operates without false sizing and crushing.

For comparison, we encourage you to test the screen-stars made by competitors
by placing a shaft, rubber cord, plastic or iron bar, rope, cord or a fairly long piece
of wood between the fingers of the screen-stars and then starting up the screening unit.
If the unit blocks or starts with great difficulty then in practice such inerts (impurities) will
be destroyed by force or crushed  or coiled or even pulled through. Consequently, the
abrasion of the screen-stars will be considerably high and the so-called “outliers”
will be in your product.

We screen with up to 50 % less expenditure of energy than usual, resulting in substantially
abrasion of our screen-stars, chains and sprockets. Screening is not a question of energy
but of intelligent acceleration and elimination of over-sized particles.

Our offer:
We do not offer any standard screening units. We design according to the material
you want to sieve and consider your requirements and wishes.



Albert Zubrägel Maschinenbau GmbH • Postfach 1106 • D-49393 Lohne • Tel.: +49 4442 6420 • +49 4442 71954