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Die verskil in doeltreffendheid tussen klein (525 kg) graad Afrikanerkoeie is bepaal ten opsigte van reproduksievermoe van koei, oorlewing en groei van nageslag en totale winsgewendheid.Koei-doeltreffendheidsindekse (K.D.I.) is bereken deur die kalf se speengewig by 260 dae, gekorrigeer vir maand van geboorte en ouderdom van koei, uit te druk as 'n persentasie van die koei se metaboliese gewig. K.D.l. is omgekeerd eweredig tot grootte van koei. 'n Positiewe en kurviliniere verwantspap bestaan tussen grootte van koei en grootte van kalf by speen. Kalfpersentasie en oorlewingspersentasie van nageslag het toegeneem met toename in koeigrootte. Groot tipe koeie was 41 %swaarder as klein tipe koeie maar het slegs 29%meer voedingstowwe benodig vir onderhoud.Soortgelyk benodig middelmatig groot koeie 15%meer voedingstowwe maar is 21 %swaarder. Die massa van twee en drie jaar oud verse en die voor slagting, karkasmassa en karkasgraad van die osnageslag van koeie van verskillende grootte is vergelyk. Die winsgewendheid van stelsels waarin klein, middelmatig en groot tipe koeie gebruik is, is bepaal. Die stelsels is op 'n grootvee-ekwivalent van 988 grootvee-eenhede per 6 000 ha vergelyk. Groot en middelmatig groot koeie was meer doeltreffend as klein koeie in terme van vleisproduksie per koei, per grootvee eenheid van 454 kg. en per hektaar. Die bruto-wins van stelsels waarin groot en middelmatig groot koeie gebruik is, en waarin klein koeiegelyk aan 100 gestal word, was 126,9 en 111,5 respektiewelik. SUMMARYThe efficiences of small (525 kg) size grade Africander cows were compared for reproductive performance of cow, survival rates, growth of progeny and overall profitability. Cow efficiency index (C.F.I) calculated by expressing the 260-day weaning mass of the calf corrected for month of birth and age of dam, as a percentage of the dam's metabolic size, is inversely related to cow size. The relationship of cow and calf mass is positive and curvilinear. Calving percentages and survival rates of progeny improved with an increase in size of cow. Large cows were 41 % heavier than small cows but required only 29 % more nutrients for maintenance. likewise medium cows required 15% more nutrients but were 21% heavier. Mass of female progeny at 2 and 3 years of age and preslaughter mass, carcass mass and carcass grades of steers from the various categories were compared. The economic efficiencies of small, medium and large size cows were assessed, based on an equivalent number of 988 livestock units per area of 6 000 ha, Large and medium size cows were more efficient producers than small cows in terms of beef produced per cow, per livestock unit of 454 kg and per hectare. Relative to small cows = 100, the gross margin for medium size cows was 111,5 and for large cows 126,9.

In April 2013 a 48 MVA submerged arc furnace producing silicomanganese was excavated in South Africa. Since the high shell temperatures recorded in the tap-hole area resulted in the furnace being switched out for relining, the tap-hole area was excavated systematically. A refractory wear profile of the tap-hole area with affected hearth and sidewall refractory was obtained in elevation. The carbon ramming paste in front of, above, and below the tap-hole was worn, as was the SiC with which the tap-hole was built. A clay mushroom formed but was detached from the refractories. Thermodynamic and mass-transfer calculations were conducted to quantify the potential for wear by chemical reaction between refractory and slag and refractory and metal in the tap-hole area. It was found that chemical reaction between refractory and slag or metal could offer only a partial explanation for the wear observed; erosion is expected to contribute significantly to wear.