US 2026/0209874 A1Published application

Process and plant for slag treatment

AssigneeDanieli & C. Officine Meccaniche SpA

InventorsAlessandra PRIMAVERA, Selena TIBURZIO

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Abstract

The invention concerns a process and a relative plant for valorizing the slag deriving from the production of steel, in an electric arc furnace. Using the principle of metallothermy, the slag is treated with aluminium and/or silicon scrap, for example from disused photovoltaic cells, to transform the iron oxides and any oxides of other alloying metals of steel respectively into Iron and ferroalloys while converting at the same time aluminium and silicon into respective oxides. In this way, the metals of the steel are recovered from the starting slag and a slag is obtained that can be used preferentially but not only in the production of cement. The process takes place passively, without additional external energy inputs, and preferably at the same time as steel production allowing continuous treatment of the black slag each time it is produced by a steel production cycle.

Claims21

Dependent claims

A process for the treatment of slag coming from the production of steel by electric arc furnaces, defined as starting slag, comprising the following steps:

(i) mixing said starting slag, comprising iron oxides, with aluminium scrap and/or silicon scrap;
(ii) metallothermic reaction between said iron oxides, with said aluminium scrap and/or silicon scrap with the consequent production of
(a) Iron, and
(b) aluminium (Al2O3) and/or silicon (SiO2) oxide in admixture with other pre-existing oxides in the slag;
(iii) separation (α) of the Iron, and (β) of the treated slag with reduced iron oxide content, which incorporates said aluminium (Al2O3) and/or silicon (SiO2) oxides formed in step (ii),
wherein the reaction of step (ii) occurs with still-liquid slag directly coming from the electric arc furnace, due to the exothermicity of the reaction itself and the heat provided by the still-liquid slag;
and
wherein the process for the treatment of slag
comprises before step (i) the production of steel with the simultaneous production of slag by an electric arc furnace wherein, in the terminal part of the steel production process, the slag is extracted from the furnace and at this point directly subjected, in a still liquid form, to treatment according to steps (i) to (iii) at the same time as the end of the steel production cycle and during a subsequent new steel production cycle, after the tapping of the steel produced in the previous cycle, and
wherein steps (i), (ii), (iii) are repeated with the parallel production of a new steel production heat and slag;
and
wherein step (i) occurs directly after deslagging, and/or concurrently with it, by joining the aluminium scrap and/or silicon scrap directly to the slag stream cascading out of a deslagging door forming part of the electric arc furnace.

9 more elements

Dependencies are inferred from the claim text.

Facts

Application: 19/138,952Filed 15 Dec 2023
Priority: IT 10202200002586916 Dec 2022
Published: 23 Jul 2026
Term ends: Not estimatedThe source records don’t support an estimate.

Classification11 codes

C04B 5/06
Treatment of metallurgical slag ; Artificial stone from molten metallurgical slag: ingredients, other than water, added to the molten slag or to…
C21B 15/02
Other processes for the manufacture of iron from iron compounds: metallothermic processes, e.g. thermit reduction
C22B 5/04
Dry methods smelting of sulfides or formation of mattes: by aluminium, other metals or silicon
C22B 5/10
Dry methods smelting of sulfides or formation of mattes: by solid carbonaceous reducing agents