The present disclosure discloses a decarbonation process of limestone and dolomitic limestone with CO.sub.2 recovery in a multi-shaft vertical kiln (MSVK) having three shafts with preheating, heating and cooling zones and a cross-over channel between each shaft. The method includes alternately heating carbonated materials by a combustion of a fuel with a comburent up to a temperature range in which carbon dioxide of the carbonated materials is released, the combustion of the fuel and the decarbonation generating an exhaust gas, the decarbonated materials being cooled in the cooling zones with cooling stream(s). Mixing between the exhaust gas and the one or more cooling streams is minimized. The decarbonated materials in two or three of the shafts are cooled with the cooling streams while a supply of the fuel in each shaft is stopped.

A heating system for heating composite materials includes a housing defining a cavity therein, a vertical conveyor system provided in the cavity of the housing for moving objects through the housing, and a heating arrangement provided in the housing for heating the objects that are moved through the housing. The heating arrangement may include at least one heating element provided in at least one of an upper portion of the housing and a lower portion of the housing. The heating arrangement may include at least one fan to circulate heated air generated by the heating arrangement throughout the cavity of the housing.

Process for operating a cement or lime plant comprising a cement or lime kiln and a calciner, wherein heat is generated by combustion of a fuel in the kiln and/or calciner, wherein a gas fed to the kiln and the calciner or to the calciner for combustion of the fuel contains an oxygen rich exhaust gas from a bioreactor containing photoautotrophic organisms and wherein the plant is preferably operated in the oxyfuel mode by using exhaust gas from the kiln and/or calciner together with the oxygen from the bioreactor as the gas fed to the kiln and/or calciner for combustion of the fuel.

The invention relates to an apparatus (10) for producing an expanded granulate from sand-grain-shaped material (1), comprising a furnace (2) with a substantially vertically extending furnace shaft (3) and a feed device (5) arranged above or in the upper region of the furnace shaft (3) for feeding the sand-grain-shaped material (1) to the furnace shaft (3). In order to achieve uniform expansion of the sand-grain-shaped material, the feed device (8) is formed to introduce the sand-grain-shaped material (1) in form of at least one downwardly falling curtain into the upper region of the furnace shaft (3), wherein the drop section (4) of the curtain (25) lies in a decentralised, preferably peripheral region of the furnace shaft cross-section. The invention also relates to a method for producing an expanded granulate from sand-grain-shaped mineral material.

The invention discloses a multi-stage suspension magnetizing roasting-magnetic separation system and method for refractory iron ore, which belongs to the field of mineral processing technology. This system comprises multistage suspension preheater, multistage suspension oxidizer, multistage suspension redactor, on-line grade analyzer, ore-like splitter, magnetic separator, dust remover, roots blower and other components and connection modes. The refractory iron ore treated by the present method can be produced to homogeneous magnetite or maghemite accurately, and through magnetic separation, on-line grade analyzer detection and ore-like splitter, the concentrate powder which reach the set grade can be obtained, and the unqualified ore powder enters the next stage of oxidation-reduction-magnetic separation-split treatment. Through the present system and method, products with different roasting quality can be obtained, and can avoid the phenomenon of over burning or under burning occurring in the past process and equipment.

This invention discloses a calcination process to produce high purity CO.sub.2 from solids containing CaCO.sub.3 which operates cyclically and continuously on the solids, arranged in a packed or a moving bed, and wherein each cycle comprises a first step where the combustion at atmospheric pressure of a fuel in the bed of solids containing CaCO.sub.3 heats them up to 800-900? C. and a second step wherein a vacuum pressure between 0.05 and 0.5 atm is applied to extract pure CO.sub.2 from the solids containing CaCO.sub.3 while cooling them by 30-200? C. Said combustion can be carried out directly with air, oxygen enriched air or O.sub.2/CO.sub.2 mixtures when the process is applied to the calcination of a continuous flow of limestone in a moving bed shaft kiln. The process is also applied to calcine CaCO.sub.3 formed in reversible calcium looping processes comprising a carbonation reaction step to form CaCO.sub.3 from CaO.

Process for calcining mineral rock in a regenerative parallel-flow vertical shaft furnace, containing at least two shafts (1, 2) interconnected by a gas transfer channel (3), each shaft operating alternately in firing mode and in preheating mode, the firing mode comprising a combustion of fuel in the presence of air so as to obtain a firing of the rock to give calcined rock, an emission of combustion gases, and a passage of these gases from one shaft to the other by means of said channel (3), the preheating mode comprising a heat exchange between said rock and said combustion gases from said channel (3), this process additionally comprising an injection of supplementary air into said channel (3) with oxidation of unburnt products contained in the combustion gases passing through this channel.

A system for the production of sponge iron, including a direct reduction shaft, a reduction gas source, a reduction gas container, a primary circuit for conducting at least a part of a top gas therethrough, a secondary circuit for conducting at least a portion of gas removed from gas conducted through the primary circuit, said secondary circuit being connected in one end to the primary circuit and in another end to the reduction gas container, a second gas line connecting the reduction gas source with the reduction gas container, and a third gas line connecting the reduction gas container with the first gas line. The system also includes a control unit configured to control a flow of reduction gas from reduction gas source to the first gas line and to control a flow of reduction gas from the reduction gas container to the first gas line through the third gas line, wherein the control unit is configured to enable a flow of reduction gas from the reduction gas container to said first gas line while correspondingly reducing a flow rate of reduction gas from the reduction gas source to said first gas line.

A method for producing direct reduced iron having increased carbon content, comprises delivering each of the herein-described mixed carburizing gas streams, which are of different composition, to a transition zone of a direct reduction furnace, and exposing partially or completely reduced iron oxide to the mixed carburizing gas streams to increase the carbon content of resulting direct reduced iron to greater than 4.5 wt. %.

Provided are a heat treatment apparatus for carbonaceous grains and a method therefor allowing drifts and internal clogging in a direct energizing furnace to not occur, allowing heat treatment of the carbonaceous grains to be continued uniformly at high temperatures for a prolonged period of time, and allowing productivity and workability to be improved. A conductive tubular structure 14 is electrically connected to an upper part of a lower electrode 13 in a manner of surrounding an upper electrode 12. The rate of change between the specific electrical resistivity of grains when grains are lightly filled and the specific electrical resistivity of grains when the grains are tap filled is defined (1-tap filling/lightly filling)100, and the rate of change is equal to less than 70%.