Abstract: An interlocking checker brick used to form a checkerwork for use in recovering heat in thermal regenerators and recuperators. The checker brick is made of a refractory material and comprises a rectangular top, a rectangular base, two side walls and two end walls. The end walls have a trapezoidal shape and therefore each side wall forms an acute angle with respect to the base. This provides a brick that tapers in thickness from the base to the top and is trapezoidal in cross section. Checkerworks utilizing these bricks are arranged to improve the amount of exposed brick surface that acts as a thermal surface and to increase turbulence while reducing laminar flow during alternating cycles of flowing gases and air.

Abstract: A nozzle for discharging molten metal from a vessel includes a porous inner sleeve surrounded by an impervious outer sleeve. The outer sleeve is cast in-situ around the inner sleeve, and is bonded in-situ to the outer surface of the inner sleeve in bonding areas adjacent its opposite ends. A gas chamber is defined between the inner and outer sleeves for receiving pressurized gas which passes through the inner sleeve to inhibit clogging and deterioration of the inner sleeve by molten metal and impurities. The gas chamber is formed by placing a heat fluidizable material around a portion of the inner sleeve before the outer sleeve is cast thereon. After casting of the outer sleeve, the assembly is heated to a temperature for fluidizing the fluidizable material which then escapes through the porous sleeve to leave a hollow gas chamber.

Abstract: A high alumina ceramic composition has controlled small amounts of MgO and CaO. When refractories made from the composition are fired, the alumina and MgO react to form spinel. The CaO promotes such reaction while minimizing undesirable expansion, and results in a refractory having significantly improved hot strength and other desirable physical properties.

Abstract: A refractory brick for use in rotary cement kilns has improved properties by the addition of small quantities of MnO.sub.2 to the composition used to form the brick.

Abstract: A checker brick has a plurality of walls intersecting at a plurality of spaced intersections. Four walls extend outwardly from each intersection in equidistantly-spaced relationship to one another. One of the four walls at each intersection is a common wall that extends between adjacent intersections. The other three walls at each intersection are independent walls. Mating projections and recesses are provided on the opposite surfaces of the brick at the intersections for interlocking bricks stacked in tiers.

Abstract: A ladle of the type having a bottom wall, sidewall and opposite trunnions extending outwardly from an upper portion of the sidewall is provided with a refractory lining by positioning a mandrel inside of the ladle in spaced relationship to the walls thereof to define a castable space. The mandrel is attached to an elongated horizontal support which extends over the top of the ladle. The elongated horizontal support is supported by the ladle trunnions and is also locked thereto against upward displacement. At least a portion of the mandrel which cooperates with the ladle sidewall is expandable and collapsible toward and away from the ladle sidewall. After the castable space is filled with castable refractory material, such material is allowed to solidify, and the elongated horizontal support is released from the trunnions so that the support and mandrel attached thereto can be lifted upwardly.