Abstract: A downhole borehole cleaning apparatus (10) for recirculating drill cuttings contained in a downhole borehole is provided and has a body (10) having an outer surface for contacting downhole fluid containing said drill cuttings, the downhole fluid comprising a certain pressure within the downhole borehole (16). The body (10) has a pair of bearing surfaces (30U; 30D) spaced apart along the longitudinal axis of the body (10), and the pair of bearing surfaces (30U; 30D) comprise substantially the same maximum outer diameter (d1) which is greater than the maximum outer diameter of the rest (14) of the body (10). Each of the pair of bearing surfaces (30U; 30D) comprises a substantially constant and un-interrupted diameter (d1) around its whole outer circumference for at least a portion of its longitudinal length; this forces all of the drilling fluid to pass around that maximum outer diameter.

Abstract: A downhole borehole cleaning apparatus (10) for recirculating drill cuttings contained in a downhole borehole is provided and has a body (10) having an outer surface for contacting downhole fluid containing said drill cuttings, the downhole fluid comprising a certain pressure within the downhole borehole (16). The body (10) has a pair of bearing surfaces (30U; 30D) spaced apart along the longitudinal axis of the body (10), and the pair of bearing surfaces (30U; 30D) comprise substantially the same maximum outer diameter (d1) which is greater than the maximum outer diameter of the rest (14) of the body (10). Each of the pair of bearing surfaces (30U; 30D) comprises a substantially constant and un-interrupted diameter (d1) around its whole outer circumference for at least a portion of its longitudinal length; this forces all of the drilling fluid to pass around that maximum outer diameter.

Abstract: A converter for the production of steel from solid and/or liquid charging substances, such as pig iron and/or scrap and/or sponge iron, includes a refractorily lined refining vessel, a refining device for feeding oxygen or an oxygen-containing gas, and a heating device. In order to obtain the maximum output possible at high scrap charging as well as a high purity of the steel, the heating device includes at least one self-consuming graphite electrode and the refining device, independent of the heating device, either is formed by an oxygen-blowing lance or includes oxygen-containing bottom and/or lateral tuyeres located below the melt bath level.