US 5,047,083 A · Process for de-oiling mill scale

Abstract

A process for de-oiling mill scale which comprises (a) collecting mill scale and analyzing for oil content; and then (b) slurrying the portion of mill scale containing more than 0.5 weight percent oil in water to achieve an aqueous mill scale slurry having at least 25 weight percent solids content; and then (c) high shear agitating the aqueous mill scale slurry to form a reduced oil mill scale suspension in an oily water emulsion; and then (d) phase separating the reduced oil mill scale from the oily water emulsion forming a reduced oil mill scale and an oily water emulsion; and then (e) fresh water rinsing the reduced oil mill scale to form an oil-free mill scale and a waste wash water; and then (f) recycling the waste wash water to form at least a portion of the aqueous mill scale slurry of step b; and then (g) repeating steps (a) through (f) until the oil-free mill scale contains less than 0.5 weight percent oil; and then (h) drying the oil-free mill scale for use to form sinter plant feed in the steel making process.

Claims16

Dependent claims

A process for de-oiling oily mill scale which consists essentially of

(a) collecting oily mill scale and analyzing for oil content;
and then
(b) slurrying a portion of oily mill scale containing more than 0.5 weight percent in oil in water to achieve an aqueous mill scale slurry having at least 25 weight percent solids content;
and then
(c) high shear agitating the aqueous mill scale slurry to form a reduced oil mill scale suspension in an oily water emulsion;
and then
(d) phase separating the reduced oil mill scale from the oily water emulsion forming a reduced oil mill scale and oily water emulsion;
and then
(e) fresh water rinsing the reduced oil mill scale to form an oil-free mill scale and a waste wash water;
and then
(f) recycling the waste wash water to form at least a portion of the aqueous mill scale slurry of step b;
and then
(g) repeating steps (a) through (f) until the oil-free mill scale contains less than 0.5 weight percent oil;
and then
(h) drying the oil-free mill scale for use to form sinter plant feed in the steel making process.

12 more elements

A process for de-oiling steel mill generated oily mill scale to form a dried oil-free mill scale useful to make steel, which process consists essentially of:

(a) collecting oily mill scale to obtain an oily mill scale having at least 0.5 weight percent oil;
and then
(b) slurrying a portion of oily mill scale containing at least 0.5 weight percent oil with water to form an aqueous mill scale slurry containing at least 25 weight percent mill scale solids;
and then
(c) agitating the aqueous mill scale slurry to dissolve or disperse easily removed oils in the water phase of the slurry;
thereby forming a suspension of partially de-oiled mill scale in an oily water phase;
and then
(d) phase separating the partially de-oiled milled scale from the oily water phase by at least one of the phase separation techniques chosen from the group consisting of filtration, settling, centrifugation, and decantation;
and then
(e) collecting and reslurrying the partially de-oiled mill scale in fresh water to form a reduced oil mill scale in fresh water to form a reduced oil mill scale slurry, and collecting and recycling the oily water phase to be used to make up at least 10 volume percent of the water used to form the aqueous mill scale slurry of step (b), and then
(f) high shear agitating the reduced oil mill scale slurry for sufficient time and at sufficient temperature to form an oil free mill scale suspension in an oily waste emulsion;
and then
(g) phase separating the oil-free mill scale from the oily waste emulsion to form a wet particulate oil-free mill scale and an oily waste emulsion;
and then
(h) fresh water rinsing the wet particulate oil-free mill scale to form a water rinsed oil-free mill scale and a waste wash water;
and then collecting the water rinsed oil-free mill scale and recycling the wash water to make up a portion of the aqueous mill scale slurry;
and then
(i) repeating steps (e) through (h) using at least a portion of the water rinsed oil-free mill scale to make up the partially de-oiled mill scale slurry, until at least a major portion of the water washed oil-free mill scale contains less than 0.5 weight percent oil;
and then
(j) drying that portion of water rinsed oil-free mill scale containing less than 0.5 weight % oil to form a dried oil-free mill scale;
and then
(k) using as at least one source of iron the dried oil-free mill scale to make steel.

19 more elements

Dependencies are inferred from the claim text.

Process for de-oiling mill scale

Life of this patent

Process for de-oiling mill scale

Life of this patent

Abstract

Claims16