Environmental　friendly　recycling　process　for　Nd-Fe-B　sintered　magnet　sludges　generated　in　the　manufacturing　process,　which　contain　large　amount　of　rare　earth,　including　Nd,　Pr　and　Dy,　is　badly　needed　so　far.　In　present　study,　we　have　developed　an　effective　route　to　obtain　recycled　sintered　magnets　from　Nd-Fe-B　sintered　magnet　sludges　by　calcium　reduction-diffusion　(RD)　process.　Compared　to　conventional　recycling　process,　our　research　is　focused　on　recovering　most　of　the　useful　elements,　including　Nd,　Pr,　Dy,　Co,　and　Fe　together　instead　of　just　rare　earth　elements.　To　improve　the　recycling　efficiency　and　reduce　pollution,　the　co-precipitating　parameters　were　simulated　and　calculated　using　MATLAB　software.　Most　of　useful　elements　were　recovered　by　a　co-precipitation　method,　and　the　obtained　composite　powders　were　then　directly　fabricated　as　recycled　Nd-Fe-B　powders　by　a　calcium　reduction-diffusion　(RD)　method.　The　recovery　rates　are　98%,　99%,　99%,　93%,　and　99%,　for　Nd,　Pr,　Dy,　Co,　and　Fe,　respectively.　The　amount　of　useful　elements　contained　in　the　recovered　composite　powders　is　greater　than　99.71　wt%.　The　process　of　RD　for　synthesizing　Nd2Fe14B　and　subsequently　removing　CaO　was　thoroughly　investigated.　Furthermore,　the　recycled　Nd-Fe-B　magnet　exhibits　a　remanence　of　1.1　T,　a　coercivity　of　1053　kA/m,　and　an　energy　product　of　235.6　KJ/m(3),　respectively,　indicating　that　recycled　Nd-Fe-B　sintered　magnet　was　successfully　recovered　from　the　severely　contaminated　sludges　via　an　effective　recycling　route.　(C)　2018　Published　by　Elsevier　B.V.　on　behalf　of　Chinese　Society　of　Rare　Earths.