New views on the hypothesis of respiratory cancer risk from soluble nickel exposure; and reconsideration of this risk's historical sources in nickel refineries

Table 1 KNR Process Flow Descriptions in Figure 1

Process Flows	Description
(2) to (3)	Ground matte lifted to roasters @ 25 m elevation using bucket elevators (144 t/day)^a
(3) to (3)	Cooled calcine to air classification in closed circuit regrind @ 35 m elevation (216 t/day)
(3) to (6)	Calcine to copper leach (205 t/day)
(6) to (5)	Residue fine fraction to anode smelting (97 t/day)
(5) to (9)^b	Anodes to Ni electrorefining
(6) to (4)	Residue coarse fraction to Mond reducers before 1953 (hydrogen reduction after) (46 t/day)
(4) to (10)	Reduced Cu leach residue to copper cementation (38 t/day)
(10) to (3)	Cement Cu (17 t/day) and dried cement Cu slimes (23 t/day) to roasters^c
(10) to/from (11)^d	Cement Cu slimes to drying (40 t/day) before transfer to roasters^c
(10) to (15)	Crude Cobaltic Hydroxide to Cobalt refinery

Sources: Thornhill (1986) [F2] and [F4]. ^a Ni substances handled daily in fine solids form (averages daily tonnages in 1958). ^b Includes deliver of anodes from building # 4 or 13 to # 11, 21, 22 or 23. ^c High As dust levels before 1953. ^d Building # 11 is a 3storey structure containing 32 Cu cementation tanks, extending through 1^st and 2^nd floors, and loaded from the 3^rd floor; 13 cement Cu filters (3^rd floor); 2 cement Cu driers (1^st floor); 15 Co precipitate filters (3^rd floor); 16 Fe precipitate filters (3^rd floor); 8 anode slime filters & 13 clarification filters (2^nd floor); and 6 Fe precipitation tanks (1^st floor). Workers in this section were classified as electrolysis workers. See Figures 4 and 5.