Behaviour of kaolinite coated olivine pellets in blast furnace

Abstract

Production olivine fluxed blast furnace pellets were coated with a water based slurry of kaolinite to give a coating of 5 kg t^-1 pellets. The LKAB experimental blast furnace in Lulea? was used to compare the behaviour of kaolinite coated olivine pellets (MPBO-KA) with that of regular olivine pellets coated with a water spray (MPBO-WA). Blast furnace operation with the kaolinite coated pellets was more stable, with higher productivity and slightly lower reductant consumption, than operation with the normal water coated pellets. In the lower shaft of the furnace, significant quantities of potassium oxide were found to have reacted with the olivine pellets and also with the kaolinite coating.     

28—SOME FACTORS INFLUENCING PUCKERING AND COCKLING IN FULLY FASHIONED GARMENTS

A simple technique for the planning of rib cuffs and welts for fully fashioned garments that is based on the classical knitting geometry of plain and 1 × 1 rib fabrics is described. The effects of cover factor and some common loop ratios at the join of 1 × 1 rib and plain fabrics on puckering at the knitted join and the effects of cover factor and some yam characteristics on cockling in plain-knitted fabrics are given.     

16—THE PREPARATION,FINE STRUCTURE,AND PHYSICAL PROPERTIES OF PARTLY METHYLATED COTTON FABRICS

Cotton fabric has been methylated under a variety of conditions. The extent of methylation has been shown to be dependent on the time of methylation and on the degree of swelling or disruption of structure. The latter is caused by the alkali pretreatment or by the swelling of the partly methylated cellulose. Fabric physical properties have been measured and the influence of the methylation treatment has been examined.     

41—THE RETRACTION AND STRETCH OF WRAPPED ELASTOMERIC-FIBRE CORE YARNS

Equations are given that relate the structure of spirally wrapped elastomeric-fibre core yams to their stretch properties. The model employed improves upon previous ones by considering the effect of covering-yarn diameter. Graphs are given that facilitate the use of the theory for manufacturing purposes.

A comparison with available experimental data indicates an improved agreement between actual and predicted values of retraction in the most important case, where the input and output yarn lengths are measured. It is expected that the improved theory given here will show to much greater advantage with the present commercial fine-core wrapped structures.

In the special case where the wrapping or covering yarns have very low twist, the basic theory is inadequate. Modifications to account for compression of the cover yarn are accordingly included to enable an approximate relationship between yarn structure and stretch to be obtained in this case.     

35—THE PREDICTION OF STRENGTHS OF LOCKSTITCH SEAMS IN WOVEN FABRICS

An absolute method of seam-strength testing is described. The effects of fabric type and gauge length on seam strength are examined. The effects of the type of sewing thread used and various measures of thread strength on the accuracy of seam-strength prediction are also investigated.

A simple method of determining the minimum loop strength of a thread is described. The efficiency of this value, corrected for one aspect of fabric construction, for seam-strength prediction is discussed.     

Fluxless laser beam joining of aluminium with zinc coated steel

Abstract

A laser welding–brazing (LWB) process to join zinc coated steel and aluminium sheets in two different flange geometries is reported. The deep drawing steel sheets are covered by a zinc layer of maximum thickness 10 μm, and a zinc based filler wire was used in the welding experiments with a Nd–YAG laser. Because of the differences in melting temperatures between iron (1808 K), aluminium (933 K), and zinc (693 K), it is possible to weld the aluminium alloy only. Owing to the zinc coating on the steel side, a Zn–Al alloy can be brazed onto the steel without any flux agent. The inevitable formation of a Fe–Al intermetallic phase at the bondline of the weld seam and the steel can be limited to a thickness of less than 5 μm and to a proportion of the contact area only. Mechanical as well as dynamic tests show results comparable to those obtained via other joining techniques. Salt chamber corrosion tests of varnished specimens display minor damage and no decline in tensile strength.