3328 Chapter 27 



large mills tended to utilize sawdust and bark as fuel and to produce chips while 

 small mills did not, as follows: 



Proportion of output volume in 



Principal Pulp- Utilized Unutilized 

 Species and sawmill size classes product chips residue residue 



— Percent 



Hardwood 



Small 59 2 16 23 



Large 62 19 8 11 



Southern pine 



Small 55 — 11 34 



Large 55 31 13 1 



In this study, small mills were defined as those producing 3 million bd ft of 

 lumber, or less, annually. 



Among specialty mills in Arkansas, Porterfield (1975) found that post mills 

 had the largest percentage of raw material input converted to principal product 

 (73 percent), followed by furniture stock mills (61 percent), handle-stock mills 

 (51 percent), and lastly stave mills (40 percent), as follows. 



Proportion of roundwood input volume in 



Principal Utilized Unutilized 

 Product of specialty mill product residue residue 



Percent- 



Furniture stock 61 20 19 



Handle stock 51 49 



Posts 73 10 17 



Staves 40 31 29 



Residues of nine pallet plants in the Tennessee Valley averaged 30 to 40 

 percent of the lumber input (by weight) (Perry 1976). A technique for estimating 

 residue production is described in section 22-7, subsection RESIDUES FROM 

 PALLET MANUFACTURE, and in figure 22-40. 



SLABS, EDGINGS, AND TRIM 



The newest mills equipped with both chipping headrigs and chipping edgers 

 make neither slabs nor edgings but instead convert their equivalent volumes 

 directly into pulp chips (see sect. 18-9). The information below is applicable 

 only to sawmills with conventional headrigs and edgers. 



Slab yield per Mbf log scale. — Using the formulae on which the International 

 14-inch and Scribner log rules are based, Bennett and Lloyd (1974) estimated the 

 cubic-foot yield of slabs and edgings from one Mbf log scale. Condensed 

 versions of their volume tables (tables 27-142 and 27-143) indicate that the yield 

 of slabs and edgings from 1 ,000 bd ft of 6-inch logs is three to four times the 

 yield from 12-inch logs. 



