Method and arrangement for reducing impurities from a roasted molybdenum concentrate

A method for reducing impurities from a roasted molybdenum concentrate (RMC), the method comprising the steps:

• a. performing a first treatment in a first reactor (505) or a first series (511) of reactors (505, 506), on at least a portion of the RMC during a first treatment reaction time to form a first treated suspension (510, 515), the first treatment comprises a step of adding the at least a portion of the RMC (501) to water or an aqueous solution, wherein the first treated suspension (510, 515) has a temperature from 10° C. to 100° C. and a first pH value of at least 2.1 to at most 5.0;
• b. performing a second treatment in a second reactor (513) or a second series (512) of reactors (513, 514), on at least a portion of the first treated suspension during a second treatment reaction time, wherein the portion of the first treated suspension comprises RMC solids from the first treated suspension, wherein the second treatment comprises a step of adding the at least a portion of the first treated suspension (510, 515) to an acid solution to form the second treated suspension (507), wherein the at least a portion of the first treated suspension (510, 515) has a temperature less than 70° C., and wherein the second treated suspension (507) has a second pH value between 1.5 and the first pH value;
• c. separating (504) at least a portion of the second treated suspension (507) from the second reactor (513) or the second series (512) of reactors (513, 514) after the second treatment reaction time.