stated above the precipitation step 3 may be carried out in any equipment suitable for the purpose correspondingly the extraction step 4 may be carried out as liquid liquid extraction in any equipment suitable for the purpose fig3 shows by way of example simplified equipment wherewith steps 3 and 4 may be implemented a control system for the precipitation equipment 3 and the extraction equipment 4 is illustrated by a control station 35 the control station 35 may be for instance a process control system or a control room computer the flow chart of fig4 gives an example of a control procedure of the control system the control process may be fully automated or semi automated in a semi automated control process some of the control steps particularly starting and ending of the precipitation step and the extraction step may be performed manually through the control station by the operator examples of commercially available reactors applicable for use as a precipitation reactor unit 31 include oktop u00ae reactors manufactured by outotec a precipitation reactor unit 31 may comprise two or more consecutive oktop u00ae reactors whereby precipitation is carried out in two or more stages u201c incomplete u201d precipitation in accordance with the exemplary embodiments of the invention may be implemented in various ways one of which is given as an example in fig4 in the example a lithium containing raw material solution is fed into the reactor unit 31 step 42 in fig4 the composition of the raw material solution prior to precipitation is measured with suitable concentration measurement equipment in the example of fig3 the raw material solution to be fed into the precipitation reactor unit 31 passes through a measuring and sampling unit 33 that samples the solution and the samples are conveyed to.