Abstract: A fuel-fired commercial water heater has a three-pass condensing type heat exchanger disposed within its tank and having a vertical flue connected at its lower end to a central collector plenum horizontally circumscribed by an outer plenum to which an exhaust pipe is coupled. A series of vertical tube structures are disposed above and intercommunicate the central and outer collector plenums. The outlet of a fuel burner is coupled to the upper end of the flue and is operative to sequentially flow combustion gases downwardly through the flue into the central collector plenum, upwardly and then downwardly through the tube structures into the outer collector plenum and then outwardly through the exhaust pipe.

Abstract: Methods and apparatus for introducing a plurality of optical markers to a field of view, capturing a two-dimensional image of said field of view on an image plate comprising a pixel array, determining a set of marker origin offset values and using said offset values to establish a set of orientation values describing the relationship between the field of view and the image plate are disclosed. These orientation values are used to relate the area of image captured by each pixel in the image plate to the real world. By applying projective geometry, vector analysis and trigonometrical surveys an image analysis is conducted to establish a three-dimensional positional data set describing the three-dimensional position of regions of reflectivity in the captured two-dimensional image. From this data set a three-dimensional model of the field of view can be reconstructed.

Abstract: A process for leaching precious metals from material containing precious metals, such as oxidic and sulfidic gold-bearing ores, is disclosed. The process includes the steps of: (i) leaching the precious metal with a leach solution containing a thiosulfate-based lixiviant; (ii) treating the material by oxidising precious metal in the material into a form that is leachable in a subsequent leaching step; and thereafter as a separate step.