ROGIERS JEROEN (BE)
| WO1996037634A1 | 1996-11-28 |
| CZ293157B6 | 2004-02-18 | |||
| US5573576A | 1996-11-12 | |||
| DE4207265A1 | 1993-09-09 |
| CLAIMS
1. A method to reduce the amount of dust formation of metal oxide particles, said method comprises the step of mixing said metal oxide particles with an aqueous solution of an alkali metal silicate to form a metal oxide-alkali metal silicate.
2. A method according to claim 1 , whereby said metal oxide - alkali metal silicate comprises an agglomerate free of dust.
3. A method according to claim 1 or 2, whereby said metal oxide particles comprise iron oxide particles.
4. A method according to claim 1 or 2, whereby said metal oxide particles comprise silicon oxide particles.
5. A method according to any one of the preceding claims, whereby said alkali metal silicate comprises sodium silicate or potassium silicate.
6. A method according to any one of the preceding claims, whereby said aqueous solution of the alkali metal silicate has a concentration between 0.1 wt% and 60 wt%.
7. The use of a metal oxide-alkali metal silicate as an additive for concrete or a ceramic material.
8. The use according to claim 7, whereby said metal oxide-alkali metal silicate comprises iron oxide-alkali metal silicate. |
Method to reduce the amount of dust formation of metal oxides
Field of the invention.
The invention relates to a method to reduce the amount of dust formation of metal oxides, in particular of iron oxide.
Background of the invention.
Recycling or further processing of metal oxide particles, such as iron oxide particles, is often difficult and expensive because of dust formation.
Due to the elevated temperature obtained during the processing of a steel rod iron oxides such as FeO, Fe 2 O 3 and Fe 3 O 4 are formed on the surface of a steel rod. Also during the storage of steel rods additional iron oxides are formed.
These oxides are commonly known as rust.
To allow successful drawing of the steel, the iron oxides formed on the steel rod must be removed. This can be done in a chemical or in a mechanical process. Mechanical descaling comprises for example abrasive belting, shot blasting and reverse bending.
The iron oxide scale removed from the steel in the descaling process has to be further treated and/or recovered. This is an expensive process mainly due to the dust formation during the treatment of the iron oxide scale.
Summary of the invention.
It is an object of the present invention to provide a method to reduce the dust formation of metal oxides, in particular of iron oxide. It is another object of the present invention to provide a method to agglomerate fine metal oxide particles before they can be reused, recycled or further processed.
It is a further object of the present invention to provide the use of metal oxide-alkali metal silicate as an additive for concrete or for ceramic materials.
According to a first aspect of the present invention a method to reduce the amount of dust formation of metal oxide particles such as iron oxide particles is provided. The method comprises the step of mixing the metal oxide particles with an aqueous solution of an alkali metal silicate to form a metal oxide- alkali metal silicate.
For the purpose of the invention, alkali metal silicate is defined as a silicate of an alkali metal, i.e. a compound comprising an alkali metal oxide (MOx) and silica (SiOx).
The alkali metal silicate comprises preferably sodium silicate or potassium silicate.
The alkali metal silicate comprises preferably sodium silicate or potassium silicate or a mixture of sodium silicate and potassium silicate. Sodium silicates (Na 2 O. XSiO 2 ) is also known as waterglass.
The most important silicate variable is the ratio silica to alkali metal oxide. For the purpose of this invention the ratio is defined by the molar proportion of silica (SiO 2 ) to alkali (Na 2 O). The molar ratio is preferably between 1.6 and 3.2.
The aqueous solution of the alkali metal silicate has preferably a concentration between 0.1 and 60 wt%, as for example 10 or 30 wt%.
The alkali metal silicate and the metal oxide particles can be mixed by adding an aqueous solution of an alkali metal silicate to the metal oxide particles followed by stirring or mixing; or by adding metal oxide particles to an aqueous solution of an alkali metal silicate followed by stirring or mixing.
The metal oxide-alkali metal silicate forms an agglomerate free of dust that can be further processed or that can be recycled.
According to a further aspect of the invention, the use of a metal oxide- alkali metal silicate, in particular of iron oxide-alkali metal silicate obtained by the above mentioned method as an additive for concrete or a ceramic material is provided.
Description of the preferred embodiments of the invention. The invention is further illustrated by means of some embodiments.
A first method comprises the following steps mixing of 300 g of an aqueous solution comprising 10 wt% Na 2 O.xSiO 2 (x between 1.6 and 3.2) with 1 kg iron oxide particles, and
- stirring the solution.
The reaction product comprises an agglomerate of iron oxide-sodium silicate.
A second method comprises the following steps mixing of 300 g of an aqueous solution comprising 30 wt% Na 2 O.xSiO 2 with 1 kg iron oxide particles, and
- stirring the solution.
The reaction product comprises an agglomerate of iron oxide-sodium silicate.
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