Provided are: a useful bed medium for a fluidized bed with good fluidity, the bed medium being usable in a fluidized bed furnace using biomass material and coal material as fuel; and a useful bed medium for a fluidized bed with good durability, the bed medium not easily forming an agglomerate of its particles, and being resistant to collapsing. The bed medium for a fluidized bed in a fluidized bed furnace for combusting or gasifying the fuel is formed of artificially-produced spherical refractory particles containing not less than 40% by weight of Al2O3 and not more than 60% by weight of SiO2 and having an apparent porosity of not more than 5%, and a ratio by weight of agglomerated particles in the bed medium is not more than 20% after three heat treatment tests on the bed medium at 900° C. for 2 hours under coexistence with the fuel.

Provided are: a useful bed medium for a fluidized bed with good fluidity, the bed medium being usable in a fluidized bed furnace using biomass material and coal material as fuel; and a useful bed medium for a fluidized bed with good durability, the bed medium not easily forming an agglomerate of its particles, and being resistant to collapsing. The bed medium for a fluidized bed in a fluidized bed furnace for combusting or gasifying the fuel is formed of artificially-produced spherical refractory particles containing not less than 40% by weight of Al2O3 and not more than 60% by weight of SiO2 and having an apparent porosity of not more than 5%, and a ratio by weight of agglomerated particles in the bed medium is not more than 20% after three heat treatment tests on the bed medium at 900 C. for 2 hours under coexistence with the fuel.

A thermally treated metal sheet or article as well as processes and systems for making the thermally treated sheet or article is provided. The process comprises heating and/or cooling the metal sheet by non contact thermal conduction for sufficiently long to provide a desired microstructure and mechanical properties. The process results in thermally treated metal sheets.

A thermally treated metal sheet or article as well as processes and systems for making the thermally treated sheet or article is provided. The process comprises heating and/or cooling the metal sheet by non contact thermal conduction for sufficiently long to provide a desired microstructure and mechanical properties. The process results in thermally treated metal sheets.

A method for heating at least one semi-finished metal products to be further laminated, via a heat exchanging device comprising a chamber containing solid particles, supporting means able to support semi-finished metal product and a gas injector, having the successive steps of: i. injecting a gas into said chamber so as to form a fluidized bed, ii. inserting at least one hot semi-finished metal product such that said at least one hot semi-finished metal product is able to transfer heat to said fluidized bed, iii. inserting said at least one semi-finished metal product to be further laminated such that said fluidized bed is able to transfer heat to said at least one semi-finished metal product to be further laminated, iv. taking out said at least one semi-finished metal product to be further laminated of said fluidized bed when the temperature of said at least one semi-finished metal product to be further laminated is less than 100 C. below the temperature of said fluidized bed.