A method is provided for combusting a metal M, selected from alkali, alkaline earth metals, aluminum, and zinc, and alloys and/or mixtures thereof, using a combustion gas. The combustion is performed using a porous burner including a porous tube as the burner. A device for performing such method is also disclosed, as well as the use of a porous burner including a porous tube as the burner for combusting the metal M using the combustion gas.

A method is provided for separating offgas from solid and/or liquid reaction products in the combustion of a metal M selected from alkali metals, alkaline earth metals, Al and Zn, and mixtures thereof, with a combustion gas. In a reaction step, the combustion gas is combusted with the metal M, forming offgas and further solid and/or liquid reaction products, and, in a separation step, the offgas is separated from the solid and/or liquid reaction products. In the separation step, a carrier gas is additionally added and the carrier gas is removed as a mixture with the offgas.

The present invention relates to an iron fuel boiler process for iron fuel combustion, comprising the steps of combusting an iron fuel suspension medium comprising iron fuel and oxygen in an iron fuel burner arrangement to obtain an iron oxide containing medium; receiving the iron oxide containing medium into an iron fuel boiler arrangement for transferring the iron oxide containing medium towards a separation unit disposed at the end of said iron fuel boiler arrangement; exchanging heat between the iron oxide containing medium and a boiler of the iron fuel boiler arrangement with a heat-exchange medium during the transfer of the iron oxide containing medium through said iron fuel boiler arrangement; and separating iron oxide from the oxide containing medium to obtain solid iron oxide particles and a gas flow. The process further comprising the step of cooling said iron oxide containing medium with a cooling medium during said transfer of the iron oxide containing medium through the iron fuel boiler arrangement such that a temperature of the iron oxide is achieved of below the sintering temperature of the particles at said separation unit.