C—3a,

33

Table 5.—Laboratory Grinding Tests of New Zealand and North American Woods: Grinding, Yield, Power, and Production Data.

5—C. 3a

(All quantities oven-dry basis.) g * I Yield of Screened Pulp. Power Requirement. t Temper- Screen- TA _. • ProducGrinder- SDecies Surface of Ston ature ' Wood 1 tags per Du ™tion tion per I Per Ton run No. Species sunace ot ston of Stock ground. From Per Per 1001b. of ,, 1 ™ e " ty „ . . per Cvltader Wood t in Pit ' 1 Wood 100 lb. of 100 cub. ft. Wood. Grinding. four During Input to Twenty . Cylinder, wood.f | ground. Wood. ! of Wood. Hours. Run. ! Grinder. fQur Hours. lb./sq. in. lb./sq. in. Deg. C. lb. lb. lb. lb.i lb. Min. Tons, j KW.H. H.P.§ ri.P. 1 Spruce .. Dressed with 8-point straight-cut burr. Stone 40 23 50 49-0 42-1 86-0 2,060 1-0 55 0*55 22 28 51 sharp 2 Insignis pine .. Stone as left from run 1. Medium sharp .. 40 23 60 39-7 31-6 79-7 1,990 1-9 55 0-41 30 39 94 3 Spruce .. Dressed with 8-point straight-cut burr. Stone 30 17 55 54-3 41-8 77-0 1,850 0-4 72 0-42 34 34 80 sharp 4 Insignis pine .. Stone as left from run 3. Medium sharp .. 30 17 55 45*8 37-2 81-1 2,030 0-2 125 0-21 37 21 97 5 Spruce .. Dressed with 8-point straight-cut burr. Stone 20 11 55 59-6 41-7 69-8 1,680 0-6 155 0-19 50 23 118 sharp 6 Insignis pine .. Stone as left from run 5 dressed with 3-point 40 23 48 36-9 28-6 77-5 1,940 j 3-2 50 j 0-41 27 38 93 straight-cut burr. Stone very sharp 7 Insignis pine .. Stone left from run 6. Sharp. .. .. 30 17 55 39-6 34-4 86-8 2,170 : 1-3 55 0*45 30 39 85 8 Insignis pine .. Dressed with 8-point straight-cut burr for first 30 to 16 to .. I .. .. .. | .. ( .. 330 part of run ; last part of run, 3-point straight- 40 22 .! cut superimposed upon 8-point straight-cut 9 Spruce .. - Stone as left from run 8 dressed lightly with 8- 30 to 16 to .. .. .. .. .. I .. 210 point straight-cut burr 40 22 10 Tawa .. Stone as left from run 9 dressed lightly with 10- 30 17 55 j 64-2 46-7 72*7 2,620 j 0-03 85 0*40 31 26 66 point spiral-cut burr. Stone dull 11 Tawa .. Stone as left from run 10 .. .. .. ! 40 23 55 64-9 52*4 80-7 2,900 0-03 65 0-58 28 31 53 ' 12 Tawa .. Dressed lightly with 8-point straight-cut burr. 30 17 55 i 64-2 55-0 85-6 3,080 ! 0*03 55 0-72 21 27 38 Stone medium sharp 13 Insignis pine|| .. Stone dressed with 8-point straight-cut burr. 35 19 55 .. .. .. .. .. : .. .. .. .. j Medium sharp 14 Insignis .. Stone as left from run 13. Medium sharp .. 35 19 55 .. .. .. .. .. .. 15 Tawa .. Stone as left from run 14. Moderately dull .. i 30 17 .. .. .. .... .... 16 Insignis pinejj .. Stone dressed with 8-point straight-cut burr. I 35 19 Fairly sharp 17 Insignis pine 1 !! .. Stone as left from run 16. Sharp ., 30 and 17 and .. .... .... 25 14 I | 18 Insignis pine**.. Stone as left from run 17. Sharp .. .. 30 17 .. j .. j .. .. .. .. .. .. j * The peripheral speed of the stone was 3,000 ft. per minute. t The average area of wood against the stone was estimated to be 74 sq. in. J The oven-dry weights per cubic foot, green volume, without bark, for insignis pine and tawa were found to be 25 lb. and 36 lb. respectively. The value used for white-spruce was 24 lb. per cubic foot as given in U.S. Department of Agriculture Bulletin No. 1485. § The power required by the motor was corrected for the motor efficiency (91 per cent.) and efficiency in the belt transmission (97 per cent.) to obtain the power input to the grinder. _ || Wood selected free of blue stain. Centre of billets bored out and knots removed. Wood contained blue stain. Centre of billets bored out and knots removed. ** Mixture of blue-stained and uninfected wood. Centre of billets bored out and knots removed.