FIELD OF INVENTION:
This invention relates to a method for estimation of oil content in mill scale and
mill sludge.
BACKGROUND OF THE INVENTION:
Iron and steel making processes in any integrated steel plant generate large
quantities of mill scale and mill sludge. Though these materials contain high iron
contents, they are unfit for use due to the large amounts of oil content present in
them as they could affect the sinter bed and ESP. Therefore controlling the oil
content in these materials would enable them to have great potential for re use in
sinter making process.
Typical compositions of Mill scale and Mill Sludge are given below:

After sufficient literature survey and pilot plant trials the specification of oil
content in both these materials was fixed as 0.7% max. But for daily process
control activity the determination of oil content in this was of utmost importance
and accordingly a method for this necessary. There was no readily available
procedure available for the same and therefore a rapid method has been
developed for the same.
OBJECTS OF THE INVENTION:
An object of this invention is to propose a method for estimation of oil content in
mill scale and mill sludge;
Another object of this invention is to propose a method for estimation of oil
content in mill scale and mill sludge which is simple;
Further, object of this invention is to propose a method for estimation of oil
content in mill scale and mill sludge which is rapid.
DESCRIPTION OF THE INVENTION:
According to this invention there is provided a method for estimation of oil
content in mill scale and mill sludge comprising the steps of:

a) mixing the mill scale and mill sludge with an organic solvent in a pre
weighed container (W1);
b) subjecting the mixture to the step of heating;
c) cooling the mixture;
d) filtering the mixture to separate the filtrate;
e) subjecting the filtrate to the step of evaporation;
f) weighing the container again after evaporation (W2);
g) calculating the oil content by the formula:
% Oil=W2-W1 / wt. of sample.
One gram of sample mill scale and mill sludge is taken in a pre weighed beaker
(W1) and mixed with an organic solvent. The entire mixture is warmed up to 60
deg C to 65 deg C for about five minutes. It is then allowed to cool. The entire
contents are then filtered through whatman 40 filter paper. The filtrate is collected
in the original pre weighed beaker (W1). The entire process is repeated once
again to ensure that all the oil has dissolved in the solvent. The solvent is then
evaporated in a drying oven at about 80 deg C and the beaker then cooled and
reweighed (W2). The oil content is calculated by the formula given below:
% Oil=W2-W1 / wt. of sample.

Based on the fundamental knowledge of the miscibility of oils with organic
solvents, trails were undertaken with a variety of solvents like petroleum ether,
chloroform, isopropyl alcohol and acetone using a synthetically prepared
standard sample.
The standard sample has been prepared by mixing 200 gms to 210 gms of dry
mill scale 1 gm to 1.05 gm of oil to give a theoretical value of 0.5% oil content.
This mixture has been treated with each of the four solvents mentioned above
using the method described above and the % age oil determined. The analysis
was carried in triplicate.

The above results indicate that using petroleum ether, the oil content obtained is
closest to the theoretical value of 0.5%.
Therefore Petroleum Ether has been selected as the solvent of choice for the
method of determination of oil content in mill scale.

EXAMPLE:
Method of oil estimation in mill scale and mill sludge
One gram of sample mill scale and mill sludge is taken in a beaker and mixed
with an organic solvent. The entire mixture is warmed up to 60 deg C for five
minutes. It is then allowed to cool. The entire contents are then filtered through
whatman 40 filter paper. The filtrate is collected in another pre weighted beaker
(W1). The entire process is repeated once again to ensure that all the oil has
dissolved in the solvent. The solvent is then evaporated in a drying oven at about
80 deg C and the beaker then cooled and reweighed (W2). The oil content is
calculated by the formula given below:
% Oil=W2-W1 / wt. of sample.
Based on the fundamental knowledge of the miscibility of oils with organic
solvents, trails were undertaken with a variety of solvents like petroleum ether,
chloroform, isopropyl alcohol and acetone using a synthetically prepared
standard sample.
The standard sample has been prepared by mixing 200 gms of dry mill scale with
1 gm oil to give a theoretical value of 0.5% oil content. This mixture has been
treated with each of the four solvents mentioned above using the method
described above and the % age oil determined. The analysis was carried in
triplicate.

WE CLAIM:
1. A method for estimation of oil content in mill scale and mill sludge
comprising the steps of:
a) mixing the mill scale and mill sludge with petroleum ether 60-
80°C or in a pre weighed container (beaker of 100 ml capacity);
b) subjecting the mixture to the step of heating at 60-85°C for 5
minutes by mantle heater (having auto cut means);
c) cooling the mixture;
d) filtering the mixture to separate the filtrate and collect in a pre
weighed beaker of 100 ml capacity (W1);
e) subjecting the filtrate to the step of evaporation at 70-80°C in a
drying oven (11);
f) cooling and weighing the container again after evaporation (W2);
characterized in that the difference of weight of container after
evaporation and weight of empty beaker give direct percentage of oil
present in a known weight of sample.

The present invention relates to a method for estimation of oil content in mill
scale and mill sludge comprising the steps of mixing the mill scale and mill
sludge with petroleum ether 60-80°C or in a pre weighed container (beaker of
100 ml capacity and subjecting the mixture to the step of heating at 60-85°C
for 5 minutes by mantle heater (having auto cut means) and cooling the
mixture and filtering the mixture to separate the filtrate and collect in a pre
weighed beaker of 100 ml capacity (W1) and subjecting the filtrate to the step
of evaporation at 70-80°C in a drying oven (11) and cooling and weighing the
container again after evaporation (W2) characterized in that the difference of
weight of container after evaporation and weight of empty beaker give direct
percentage of oil present in a known weight of sample.