KR20070004538A - Recovery of metallic and non-metallic values from slag - Google Patents

Abstract

A process for the recovery of metallic and non-metallic values from slag comprising adding a mixture of reagents to steel slag at a predetermined rate followed by recovering the metallic values there from. ® KIPO & WIPO 2007

Description

RECOVERY OF METALLIC AND NON-METALLIC VALUES FROM SLAG}

The present invention relates to the recovery of metal and nonmetallic values from slag.

The present invention also relates to the recovery of metal and nonmetallic precious metals from the slag produced while producing steel through the addition of suitable additives.

During the production of steel, waste is produced in the form of slag, whose tonage varies from 10 to 20% of the steel produced, depending on the steel production process. This slag is used for low value applications such as landfills, road construction, ballast, etc., either immediately or after some processing. These slags contain significant amounts of calcium oxide (CaO) and oxides of iron, so the utilization of these low values is not justified for their potential usefulness.

Depending on the type of molten metal and / or steel manufacturing method employed, the following compounds limit the amount of BOF slag that can be recycled: high ratios of iron oxides and medium to high ratios of phosphorus oxide ratios and times without them. Presence of. At the same time, the fact that almost half of the slag consists of calcium oxide and almost one fifth of iron oxide means that it can be used for more suitable applications than ever before.

It is therefore an object of the present invention to propose a method of recovering metal and nonmetallic precious metals from slag in order to make the slag potentially useful.

It is yet another object of the present invention to propose a method for recovering metal and nonmetallic valuables from slag so that a larger amount of BOF slag can be recycled.

These and other objects of the present invention will become more apparent in the detailed description that follows.

According to the present invention there is provided a process for recovering metal and non-metallic precious metals from slag.

The process according to the invention comprises the addition of a selected reactant to the steel slag at a predetermined rate. The reactants to be used are mixtures having ferro silicon, carbon, spar, aluminum and lime in proportions varying from 100% to 0% of the total reactants, respectively, depending on the desired end use. Although not essential, it is preferred to add in molten state.

After the steel is discharged into the steel ladle, the slag is removed from the steel production vessel in a properly aligned slag bath. Slag pots are handled in the usual manner in a running plant, but are placed on the treatment stand after covering the openings of the bath with fireproof lined lids. The lance, made of a suitable refractory material and capable of injecting different reactants, is lowered into the slag bath, and treatment begins. After injecting the required amount of reactant, the process is stopped and the slag is granulated or discarded. A pool of molten iron formed after the reactant has reduced the iron oxide is recovered as metal earrings. Treated slag is suitable for a variety of end uses, including cement production, iron ore sinter production, desulfurization compounds, partial replacements for lime in steel processing, and more.

Pilot-level experiments in a running plant were conducted to establish the process parameters needed to reduce the oxides of iron and phosphorus. Several aspects of the process for instant flakes of treated slag have been identified. The exact amount and type of reactants used depends on the intended end use. Ferrosilicon is used at a rate of 0 to 150 kg / ton for slag, aluminum is used at a rate of 0 to 90 kg / ton for slag, and coke, spa and lime are 0 to 100, 0 to 50 and Used at a rate of 0 to 60 kg / ton. Purging gas is used from 0 to 600 liters per minute.

By using this process, the iron and phosphorus oxides in the slag can each go down 1% below their initial level. Typical results can be seen in the accompanying FIG. 1, which shows the reduction of the BOF slag. The graph shows the percentage ( ₅ ) of the reactants added over time versus the ratio of iron and phosphoric acid (P ₂ O ₅ ).

Claims (13)

A method for recovering metal and non-metallic precious metals from slag, the method comprising adding a reactant mixture to a steel slag at a predetermined rate and then recovering the metallic precious metal therefrom. The method of claim 1, wherein the reactant comprises a mixture of ferrosilicon, carbon, spa, aluminum, and lime. The method of claim 1 wherein the reactants are used in proportions that vary individually from 100% to 0% of the mixture. The method of claim 1 wherein 1 to 150 kg of ferrosilicon is added per ton of slag. The method of claim 1 wherein 0 to 90 kg of aluminum is added per ton of slag. The method according to claim 1, wherein 0 to 100 kg of coke is added per ton of slag. The method of claim 1, wherein 0 to 50 kg of spar is added per ton of slag. A process according to claim 1, wherein 0 to 60 kg of lime is added per ton of slag. The method of claim 1 wherein the purge gas passes at a rate of 0 to 600 liters per minute during the treatment. The method of claim 1, wherein the reactant is added when preferably in a molten state. The method of claim 1, wherein after addition of the reactant, the process is stopped and the slag is granulated or discarded. The method of claim 1, wherein the metallic ear is recovered from a pool of molten iron formed after the addition of the reactant. 2. Process according to claim 1, characterized in that the treated slag obtained after the recovery of the metal ear is used in cement production or iron ore sinter production or as a desulfurizing agent and as a partial substitute for lime during steel production.