. ▁▁ 1 9 4 0 ▁Oper ations ▁start ▁at ▁the ▁Krist ine berg ▁mine . ▁▁ 1 9 3 9 ▁Out ok ump u ▁O y ▁starts ▁extract ing ▁z inc ▁concent rate ▁from ▁Out ok ump u ▁ore . ▁▁ 1 9 3 1 ▁The ▁two ▁min ing ▁companies ▁– ▁V ä ster b ott ens ▁Gru v akt ie bol ag ▁and ▁Sk elle fte å s ▁Gru v akt ie bol ag ▁– ▁are ▁merged ▁to ▁form ▁Bol id ens ▁Gru v akt ie bol ag . ▁▁ 1 9 3 0 ▁Oper ations ▁start ▁at ▁the ▁R ön n sk är ▁sm elter . ▁▁ 1 9 2 9 ▁Z inc ▁production ▁begins ▁at ▁O dd a . ▁The ▁first ▁ore ▁train ▁to ▁R ön n sk är ▁leaves ▁Bol iden ▁on ▁ 2 4 ▁September . ▁▁ 1 9 2 5 ▁V ä ster b ott ens ▁Gru v akt ie bol ag ▁and ▁Sk elle fte å ▁Gru v akt ie bol ag ▁are ▁formed . ▁▁ 1 9 2 4 ▁Gold ▁discovered ▁at ▁F å gel my ran ▁in ▁Bol iden . ▁ ▁Cont ro vers y ▁In ▁the ▁mid - 1 9 8 0 s , ▁Bol iden ▁was ▁involved ▁in ▁a ▁dump ing ▁controvers y ▁in ▁Chile . ▁According ▁to ▁Business ▁& ▁Human ▁Rights ▁Resource ▁Centre , ▁" B ol iden ▁sh ipped ▁approximately ▁ 2 0 , 0 0 0 ▁t onnes ▁of ▁sm elter ▁sl ud ge ▁to ▁the ▁Pol yg