Abstract: The present invention concerns a process for producing calcium carbonate from a calcium-containing alkaline slag material, the process containing the steps of extracting the alkaline slag material in a series of extraction steps, including at least 2 extraction steps, using extraction solvent(s) containing salt in an aqueous solution, whereby a calcium-containing filtrate and a residual slag is formed in each extraction step, separating the residual slag from the filtrate after each extraction step, carrying each residual slag to the following extraction in the series of extractions, to be used as raw material in said following extraction, and discarding the residual slag separated from the last extraction, carrying each filtrate to the previous extraction in the series of extractions, to be used as extraction solvent in said previous extraction, and carrying the first filtrate, separated from the first extraction step, to a carbonating step, carbonating calcium as calcium carbonate from the first filtrate

Abstract: The object of the invention is an arrangement for communication and location tracking, which comprises at least one or more server apparatuses and a plurality of remote terminals, the position of which is arranged to be located by satellites and which comprises at least means for sending information to the server apparatus. The means in the remote terminals are equipped to send information concerning the position of the remote terminal and other information collected by the remote terminal wirelessly to the server apparatus, and the server apparatus is provided with at least connection means for receiving information coming from the remote terminal, with a database for recording information coming from the remote terminal, with processing means for processing information sent by the remote terminal, and also with a control system for coordinating and controlling the different functions of the arrangement for communication and location tracking.