ISO 17544:2004

INTERNATIONAL ISO
STANDARD 17544
First edition
2004-07-15
Carbonaceous materials used in the
production of aluminium — Cold and
tepid ramming pastes — Determination of
rammability of unbaked pastes
Produits carbonés utilisés pour la production de l'aluminium — Pâtes de
brasquage froides et tièdes — Détermination de l'aptitude au
brasquage des pâtes non cuites

Reference number
©
ISO 2004
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Foreword
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ISO 17544 was prepared by Technical Committee ISO/TC 47, Chemistry, Subcommittee SC 7, Aluminium
oxide, cryolite, aluminium fluoride, sodium fluoride, carbonaceous products for the aluminium industry.

INTERNATIONAL STANDARD ISO 17544:2004(E)

Carbonaceous materials used in the production of aluminium —
Cold and tepid ramming pastes — Determination of rammability
of unbaked pastes
1 Scope
This International Standard describes a method of producing a compaction curve indicating the rammability of
carbonaceous ramming pastes used to line cathodes utilized in the production of aluminium.
Determination of the rammability enables a ramming paste with the optimum density to be selected.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 5725-2, Accuracy (trueness and precision) of measurement methods and results — Part 2: Basic method
for the determination of repeatability and reproducibility of a standard measurement method
ISO 14422, Carbonaceous materials used in the production of aluminium — Cold-ramming pastes — Methods
of sampling
3 Symbols
h measured height of test specimen, in cm
m mass of paste placed in cylinder, in g
N number of impacts
N2 minimum value of second derivative of ρ(N)
r inner radius of rammer cylinder, in cm
α scaling or normalization parameter describing the steepness of the compaction curve (which
decreases as α increases)
γ location parameter which shifts the origin of the distribution
−3
ρ maximum value of density, in g⋅cm
max
ρ initial value of density, representative of loose compaction of the paste under its own weight,
−3
in g⋅cm
−3
ρ(N) density after N impacts, in g⋅cm
ρ(N)' first derivative of ρ(N)
ρ(N)'' second derivative of ρ(N)
ρ(N)''' third derivative of ρ(N)
−3
ρ(50) density after 50 impacts, in g⋅cm
−3
ρ(100) density after 100 impacts, in g⋅cm
−3
∆ρ pre-exponential factor, in g⋅cm : ∆ρ = ρ − ρ
max 0
4 Principle
Ramming paste is compacted in a laboratory rammer. The paste is subjected to a total of 350 impacts. The
density of the paste is measured as a function of the number of impacts. The data is fitted to a three-
parameter cumulative Weibull distribution function given by the following equation:

log N−γ

ρρ()N=−∆ρ×exp− (1)
max 
α



A ramming parameter N2, corresponding to the number of impacts for which the second derivative of the
Weibull function has a minimum value, is then calculated.
An alternative method of evaluation is to determine the ratio of the density after 50 impacts to the density after
100 impacts, as shown by the following formula:
ρ(50)
(2)
ρ(100)
5 Apparatus
An example of a rammer mould is shown in Figure 1.
5.1 Rammer cylinder, made of steel, with an inner diameter of 50 mm.
5.2 Ram base, made of steel. The ram base shall fit into the rammer cylinder and act as the bottom of the
cylinder.
5.3 Rammer, consisting of a steel piston, a falling weight mounted so that it can be dropped onto the top of
the piston, and a height-measuring device accurate to 0,1 mm. The mass of the falling weight shall be 6,35 kg
and the weight shall travel a constant distance to impact of (50 ± 0,1) mm.
5.4 Box (with lid), capable of containing the amount of ramming paste needed to produce one test
specimen. The free space over the paste shall not be more than 50 % of the volume of the paste.
5.5 Heating/cooling cabinet, capable of being maintained at a cons
...