A control system and method for dry centrifugal granulation of liquid slag are provided. The control system includes a granulator cold-air control unit and a feeding unit. The granulator cold-air control unit includes a granulator, a rotating shaft, a motor, and a cold-air supply unit. The granulator is fixed to the motor; the cold-air supply unit includes a shaft cooling air channel and an annular cooling air channel; the shaft cooling air channel consists of an inner duct sleeve and a shaft sleeve; the annular cooling air channel consists of the inner duct sleeve and an outer duct sleeve arranged at periphery of the inner duct sleeve, which have different external diameters; the feeding unit includes a slag dropping pipe arranged above the granulator; a sliding gate is arranged at a lower section of the slag dropping pipe, and an accident diversion spout is equipped.

A method of pretreatment and bromine recovery of PCB Incineration ash is disclosed that relates to the field of comprehensive recovery of valuable metals by full wet method, especially relates to a method of valuable metals and bromine recovery, precious metals enrichment in pretreatment process of PCB Incineration ash. The major steps includes alkali leaching, Cu extraction back-extraction, neutralization-precipitation to separate, Bromine evaporative crystallization, regeneration, acid pickling, Zn evaporative crystallization, removal of Zn and Cu. Compared with the traditional comprehensive recovery process of ash, the invention can separate bromine from ash and recover valuable metals such as copper, zinc and lead with the maximum extent, at the same time, the enrichment of silver and other precious metals is beneficial to the subsequent recovery of precious metals. It has high added recovery value and no tailless discharge.

A method of pretreatment and bromine recovery of PCB Incineration ash is disclosed that relates to the field of comprehensive recovery of valuable metals by full wet method, especially relates to a method of valuable metals and bromine recovery, precious metals enrichment in pretreatment process of PCB Incineration ash. The major steps includes alkali leaching, Cu extraction back-extraction, neutralization-precipitation to separate, Bromine evaporative crystallization, regeneration, acid pickling, Zn evaporative crystallization, removal of Zn and Cu. Compared with the traditional comprehensive recovery process of ash, the invention can separate bromine from ash and recover valuable metals such as copper, zinc and lead with the maximum extent, at the same time, the enrichment of silver and other precious metals is beneficial to the subsequent recovery of precious metals. It has high added recovery value and no tailless discharge.

The present invention is a CO.sub.2 based hydrometallurgical multistage reaction and separation system comprising: a pre-washing device configured to fully mix the feedstock, such as industrial solid waste, mineral and mine tailings with auxiliary reagents and water at specific ratio, a reactor configured to treat the washed slurry with CO.sub.2 bubbling and discharge the treated slurry to the next stage, multistage separators configured to separate solid particles from treated slurry and recycle the unreacted solids back into the pre-washing device, a by-product preparation device configured to generate calcium and magnesium based products from filtrate containing target elements, a water recirculating device configured to recycle the remaining liquor back to the system. The present invention ensures the whole system is able to continuously and consistently react at maximum capacity through continuous slurry feeding and CO.sub.2 bubbling into the reactors which also enables multistage circulating reaction.

The present invention discloses the systems of producing calcium and magnesium carbonate from the Ca/Mg containing solution leached by a CO.sub.2-based hydrometallurgical process which includes: a precipitation reactor that the Ca/Mg containing leached solution is continuously added and fully mixed with the alkaline reagent at specific mole ratio into the precipitation reactor and the reactor also comprises a CO.sub.2 bubbling module where CO.sub.2 is captured and recirculated from the thermal decomposition process as needed; a solid-liquid separation unit that the treated slurry is treated by the solid-liquid separation unit to produce precipitated calcium and magnesium carbonate products where the recirculating water is recycled back into the precipitation reactor; a thermal decomposition unit that the calcium and magnesium carbonate products is calcined by the thermal decomposition unit to produce an alkaline reagent and the alkaline reagent is recycled back into the precipitation reactor for the next batch of reaction.

A charged material containing alloy iron of at least one of ferrochrome containing metallic Si or ferrosilicon, and unreduced slag containing Cr oxide generated by oxidative refining, is charged into an electric furnace as a mixture in which a mass ratio of a metallic Si amount to a Cr oxide amount is from 0.30 to 0.40, and a C concentration is in a range of from 2.0% by mass to a saturation concentration, and molten iron containing Cr obtained due to the Cr oxide undergoing reduction processing is produced, such that, when the charged material is heated and melted in the electric furnace, an attainment temperature is set to from 1400° C. to 1700° C., a maximum average heating rate in any 80° C. interval from 1300° C. to the attainment temperature is set to 15.0° C./min or less, and a minimum average heating rate in any 80° C. interval from 1300° C. to the attainment temperature is set to 3.0° C./min or greater.

A charged material containing a metal raw material of at least one of ferrochromium containing metal Si or ferrosilicon and unreduced slag containing Cr oxide generated by oxidation refining is charged into an AC electric furnace including three electrodes, a mass ratio of a metal Si amount to a Cr oxide amount being from 0.30 to 0.40, and a C concentration being from 2.0% by mass to a saturation concentration, and operation is performed under a condition where a diameter PCD (m) of a circle passing through the centers of the three electrodes viewed in a plan view from a central axis direction of the electric furnace, an average electrode height H.sub.e (m) that is a vertical distance from a tip of each electrode to a molten metal surface, a furnace inner diameter D.sub.f (m), a molten slag thickness H.sub.s (m), a spreading diameter D.sub.arc (m) of an arc on the molten metal surface, and a deflection angle θ (deg) of the arc satisfy the following relationships to produce molten iron containing Cr.

D.sub.arc=PCD+2H.sub.e.Math.tan θ

θ=52.5−75.Math.(PCD/D.sub.f)

0.22≤D.sub.arc/D.sub.f≤0.30

0.35≤H.sub.e/H.sub.s≤1.50

A dross processing assembly includes a stirring station at which dross in a first dross recovery vessel is stirred and a pressing station at which previously stirred dross in a second dross recovery vessel is pressed simultaneously with the stirring of the dross in the first dross recovery vessel. The stirring station and the pressing station may be commonly housed in an enclosure. A conveyor system may advance dross recovery vessels through the dross processing assembly for continuous dross processing.

A dross processing assembly includes a stirring station at which dross in a first dross recovery vessel is stirred and a pressing station at which previously stirred dross in a second dross recovery vessel is pressed simultaneously with the stirring of the dross in the first dross recovery vessel. The stirring station and the pressing station may be commonly housed in an enclosure. A conveyor system may advance dross recovery vessels through the dross processing assembly for continuous dross processing.

A system and method directed to the economical recovery of valuable iron constituents from iron blast furnace and steel-making slag fines wherein the slag is obtained and subjected to a series of classification steps which progressively sort the slag fines by various physical characteristics, including magnetism, size, and density, into relatively iron-rich and relatively iron-poor classifications, resulting in the isolation of iron-rich commercial byproduct at one or more of the classification steps.