Abstract: A system for correlating condition-indicative signals fed sequentially from a series of sensors, such as thermocouples installed in ports on the surface of a rotating kiln at various longitudinal and angular coordinates along the total length of the kiln, with the signals printout on a multipoint recorder mounted remotely from the kiln is disclosed wherein two photoelectric devices are disposed at fixed points adjacent the kiln for sensing the passage of a series of sensor-location indicator tabs mounted on and rotating with the kiln.

Abstract: A method and means for maximizing the use of the kiln capacity in a rotary kiln, directly reducing metal oxides using solid carbonaceous materials as the source of fuel and reducant, is disclosed involving the creation of an annular dam arrangement within the kiln at a selected position between the feed end and the discharge end dams, which arrangement is located and dimensioned with respect to the end dams, such that the materials in the charge bed suitably fill the kiln volume and have sufficient residence time in the feed end portion of the kiln, to permit adequate heat transfer thereto, thus minimizing the portion of the kiln needed for preheating and maximizing the remaining portion of the kiln available for reduction.

Abstract: A method and means for improved control of the process for directly reducing materials containing iron oxides in a rotary kiln using a solid carbonaceous reducing agent, such as coal, introduced from the charge feed and discharge ends of the kiln, as the source of both fuel and reductant, and oxygen-containing gas introduced along the kiln length, is disclosed wherein the portion of the reducing agent fed at the discharge end is injected in the form of two or more streams through the discharge end of the kiln onto the charge bed in such manner as to permit close and efficient control of the process, particularly when carried out in larger kilns.

Abstract: A method for maintaining the sulfur level below 0.05% by weight, and preferably below 0.02% by weight, in the DRI product from the process for directly reducing ore containing iron oxides in a rotary kiln using a solid carbonaceous reducing agent, fed at the materials feed end and at the discharge end of the kiln, as both fuel and reductant is disclosed, identifying the important factors in the process affecting the sulfur levels in the DRI and steps and means for properly controlling these factors.

Abstract: A method and means for improved control of the process for directly reducing materials containing iron oxides in a rotary kiln using a solid carbonaceous reducing agent, such as coal, introduced from the charge feed and discharge ends of the kiln, as the source of both fuel and reductant, and oxygen-containing gas introduced along the kiln length is disclosed wherein the portion of the reducing agent fed at the discharge end is blown as a stream in a prescribed manner into the discharge end of the kiln. In particular, the important features of the stream are described including its longitudinal distribution and axial spread over the charge bed, as well as its contact region with the kiln walls and the quandrants of the kiln barrel into which it is directed, whereby the bed and gas phase temperatures may be controlled and heat transfer to the bed enhanced.

Abstract: A method and means for improving the efficiency of the process for directly reducing ore containing iron oxide in a rotary kiln using a solid carbonaceous reducing agent, such as coal, introduced from the ore feed and discharge ends of the kiln, as both fuel and reductant, is disclosed wherein the charred coal or char found in the discharge product is recycled into the process at the discharge end of the kiln rather than the feed end as in the prior art. In particular, the recovered char, both coarse and finer particles, are transported to a recycle bin from which they are returned at a preselected rate to the kiln process by being injected along with the coal blown into the discharge end of the kiln. Alternatively, the recycle char alone may be fed without any coal at the discharge end of the kiln.

Abstract: A system for monitoring the internal conditions in a rotary kiln is disclosed wherein a series of sensors, such as thermocouples, are installed in ports at various longitudinal and angular coordinates along the total length of the kiln for providing temperature signal samples in the form of sequenced millivolt signals, and a single thermocouple is provided which is insertable in a second series of ports along the kiln to permit immediate localized temperature sensing. The sequenced millivolt signals and the single thermocouple millivolt signals are both fed to respective millivolt-to-milliamp converters mounted on a heat shield on the kiln surface, which shield also mounts two sets of continuous slip rings encircling the kiln. The respective milliamp signals are communicated from the converters to the respective slip ring sets from which they are picked off by suitable stationary contact means disposed adjacent the kiln and conducted to appropriate recorders in a control room.

Abstract: A method and means for maintaining optimum operation of the process for directly reducing iron oxides in a rotary kiln, using a solid carbonaceous reducing agent, such as coal fed at both the charge feed end and discharge end as the source of fuel and reductant, and oxygen-containing gases is disclosed wherein the DRI product, charred coal or char, and fine waste found in the kiln discharge materials from the discharge end are separated and measured for fixed carbon content and the process parameters may be adjusted to optimum by establishing an appropriate percentage by weight, in the range from 5% to 15%, of fixed carbon in the total of these discharge materials.

Abstract: A system for taking samples of materials undergoing processing in a rotary kiln is disclosed in the form of a first or inner member mounted on and passing through the kiln shell and containing a chamber in direct communication with the kiln interior; a second or outer member forming an outer chamber and having one end connected to said first member; and a pivotable swing gate disposed between the inner and outer members for controlling communication between the two chambers. The outer end of the outer member has an adaptor for removably mounting a material-collecting vessel or catch can thereon. Opening of the swing gate will permit material from the kiln interior to enter the catch can without contact with the ambient environment, and subsequent closing of the swing gate permits sealing of the inner chamber in communication with the kiln interior before removal of the catch can and its contents from the end of the outer member.

Abstract: A method and means for improving the efficiency of the process for directly reducing ore containing iron oxide in a rotary kiln using a solid carbonaceous reducing agent, such as coal, introduced from the ore feed and discharge ends of the kiln, as both fuel and reductant, is disclosed wherein the charred coal or char found in the discharge product is recycled into the process at the discharge end of the kiln rather than the feed end as in the prior art. In particular, the recovered char, both coarse and finer particles, are transported to a recycle bin from which they are returned at a preselected rate to the kiln process by being injected along with the coal blown into the discharge end of the kiln. Alternatively, the recycle char alone may be fed without any coal at the discharge end of the kiln.

Abstract: In the direct reduction process for reducing iron ore to sponge iron of the type disclosed in U.S. Pat. No. 3,890,138 to Hockin wherein all of the air supply tubes along the rotary kiln inject air toward the discharge end of the kiln it has been found that by reversing the direction of injection of the air from one or more of the tubes in the preheat zone of the kiln the condition of the off-gases can be considerably improved without affecting the process in the reduction zone and ultimately the quality of the resulting product and improved preheating of the kiln charge can be effected without the formation of undesirable kiln accretions.

Abstract: A system for feeding coal or other material blown from a pipe in a desired trajectory is disclosed including a positioning device for applying directional force to the midsection of the pipe to produce slight bending for orienting the free end, which device has an horizontal adjustment member and a vertical adjustment member. Each comprising a slotted arm with an integral handle mounted on three congruent support plates and pivoted respectively in the interstices between the middle and outer plates. The plates have concentric circular openings therein through which a sleeve for passing the pipe therethrough axially extends.

Abstract: A method and means for improving control of the process for directly reducing ores containing iron oxide in a rotary kiln using a solid carbonaceous reducing agent, such as coal, introduced from the ore feed and discharge ends of the kiln, as both fuel and reductant, is disclosed wherein the temperature profile of the moving bed of solids is maintained such that the temperature is moderated to remain below the sintering temperature of the materials in the bed from the feed end zone for about the first two-thirds of the kiln length and the temperature is then maximized within sintering limitations in the working zone which is limited to about the last third of the kiln length. The temperature profile is controlled by regulating the volumes of air supplied to the kiln atmosphere from air injectors at spaced intervals along the length of the kiln, after establishing the appropriate proportion of coal steadily blown into the discharge end of the kiln for the particular process constituents being used.

Abstract: A classifying system including an air elutriation device is disclosed, which device is in the form of an upright box defining an airflow chamber open at its lower end and connected at its upper end to an exhauster device. A mixture of particulate materials is admitted into the chamber through a slot in the side of the box above a series of rods which extend across the chamber and are adjustable for varying the rate and turbulence of the airflow in the admitting zone to separate the lighter particles from the heavier particles in the mixture with the lighter particles being carried by the airflow upwardly and out of the chamber.

Abstract: In the direct reduction process for reducing iron ore to sponge iron of the type disclosed in U.S. Pat. No. 3,890,138 to Hockin wherein all of the air supply tubes along the rotary kiln inject air toward the discharge end of the kiln it has been found that by reversing the direction of injection of the air from one or more of the tubes in the preheat zone of the kiln the condition of the off-gases can be considerably improved without affecting the process in the reduction zone and ultimately the quality of the resulting product and improved preheating of the kiln charge can be effected without the formation of undesirable kiln accretions.