Neutral day plants

Lang A, Chailakhyan MK, Frolova lA (1977) Promotion and inhibition of flower formation in a day neutral plant in grafts with a short-day plant and a long-day plant. Proc Natl Acad Sci USA 74 2412-2416... 

FIGURE 10.3 Number of days until first flower (A) and the onset of tuber formation (B) in a short-day (NC10-92), intermediate ( Parlow gelb ), and day-neutral (NC10-9) clone. Tubers were planted at 2-week intervals throughout the summer. (From Kays, S J., unpublished data.)... 

Commercialization of the ammonia process was pioneered by the Consolidated Mining Smelting Company, Ltd. (Cominco), which operated a 3 ton/day sulfur-producing pilot unit at their Trail plant in 1934 and placed a 40-ton/day commercial plant in operation in 1936 (King, 1950). The sulfur dioxide recovered in these early units was reduced to elemental sulfur. Later changes in the market picture made it more economical to use the concentrated sulfur dioxide streams as feed to sulfuric acid plants. Sulfur dioxide-absorption processes using both heat and acid neutralization were developed at Trail. Present operations use the neutralization process. 

A pilot plant ia India has been estabUshed to extract fiber, pulp, and juice from the leaves of sisal plants. The fiber is sold direcdy or used to manufacture rope, the cmshed pulp is used ia paper processiag, and the juice is an excellent source of hecogenin. During a three- to five-day fermentation of the juice, partial enzymatic hydrolysis causes hecogenin to precipitate as the hemisaponin ia the form of a fine sludge. This sediment is hydrolyzed with aqueous hydrochloric acid, neutralized, and filtered. This filter cake is washed with water and extracted with alcohol. The yield of hecogenin varies between 0.05 and 0.1% by the weight of the leaf (126). 

The process flow sheet was first tested for direct leaching of steel mill flue dust and production of zinc metal by electrowinning. The tests were performed in a continuously operating pilot plant, producing 10-20 kg/day zinc metal. The same pilot plant was then used for treating copper/zinc-rich brass mill flue dust in a closed loop operation, recycling all the zinc solvent extraction raffinate to the copper circuit leach section. In the zinc circuit leach section, only the amount of zinc rich dust necessary for neutralization of the copper solvent extraction raffinate was used. The results obtained from the pilot plant tests indicated contamination problems within the solvent extraction loops. The estimation of economic data showed a weak return on the assets compared with the alkali route, and sensitivity toward the raw material price. 

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