Plant and method for treating solid material
AssigneeMetso Outotec Finland Oy
InventorsSebastian LANG, Roberto VALERY, Peter STURM, Richard HAAS-WITTMÜSS, Günter SCHNEIDER, Jan JOLK
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Abstract
The disclosure relates to a plant for thermal treatment of solid material to decrease the content of heavy metal elements. The plant comprises one reactor for heating the solid material, which is arranged to have both an oxidizing atmosphere and a reducing atmosphere, and the plant includes a hot gas generator, which is arranged to provide hot gas to the reactor. The disclosure also relates to a method for thermal treatment of solid material and to a method for producing fertilizer precursor.
Claims24
A plant for thermal treatment of solid material to decrease the content of heavy metal elements and/or other impurities, which plant comprises
- optionally at least one drying system (1,2),
- optionally at least one preheating system (3,4),
- a reactor (5) for heating the solid material to a reaction temperature,
- optionally a heat recovery system (6,7), and
- optionally a cooling system (8)
- characterized in that said plant includes only one reactor (5), and that said reactor (5) is arranged to have both an oxidizing atmosphere and a reducing atmosphere, and that the plant includes a hot gas source (9), which is arranged to provide hot gas to the reactor, wherein the reactor (5) is a rotary kiln, wherein the hot gas source is arranged to heat the solid material and provide reducing gas by counter current gas flow.
The plant according to any one of the preceding claims, wherein the hot gas source (9) is a hot gas generator.
The plant according to any one of the preceding claims, wherein the solid material is an ore, preferably a phosphate ore, preferably a phosphate ore having a phosphate content of less than 30 weight-%.
The plant according to any one of the preceding claims, wherein the hot gas source (9) is arranged to provide hot gas, preferably hot gas comprising CO and H2, into the reactor (5) at and/or near its discharge end (5-2).
The plant according to any one of the preceding claims, wherein the reducing atmosphere is arranged at and/or near the discharge end (5-2) of the reactor (5) and the oxidizing atmosphere is arranged at and/or near the feed-end (5-1) of the reactor (5).
The plant according to any one of the preceding claims, wherein the reactor (5) is a rotary kiln, which comprises at least two shell air fans (5b).
The plant according to any one of the preceding claims, wherein the reactor (5) is a rotary kiln, which comprises at least one shell air fan (5b) per every 10 meter kiln.
The plant according to any one of the preceding claims, wherein the reactor (5) is arranged to heat the solid material to a temperature of 500 to 1000° C., preferably 750 to 900° C.
The plant according to any one of the preceding claims, wherein the heavy metal elements include cadmium (Cd).
The plant according to any one of the preceding claims, wherein the plant includes at least one preheater (3) and the off-gas (5c) exiting the rotary kiln is arranged to be led to said at least one preheater (3).
The plant according to any one of the preceding claims, wherein the plant includes a pre-dryer (1) and downstream to the pre-dryer (1), a preheater (3).
A method for thermal treatment of solid material to remove heavy metal elements and/or other impurities, wherein the method comprises the following steps
- optionally drying the solid material,
- optionally preheating the solid material,
- heating the solid material in a reactor to a reaction temperature to decrease the content of heavy metal elements and/or other impurities,
- optionally cooling the heated solid material, and
- obtaining treated solid material
- characterized in that the heating is performed in only one reactor, and that said reactor has both a reducing atmosphere and an oxidizing atmosphere, and that heating of the reactor is at least partly achieved by providing hot gas via a hot gas source, wherein the reactor (5) is a rotary kiln, wherein the solid material is heated in a counter-current flow.
Dependencies are inferred from the claim text.