Process and apparatus for reducing stannic oxide into metallic tin

Abstract

Provided is a process and apparatus for reducing stannic oxide into metallic tin. The process includes: establishing at least one electrolytic cell; feeding the stannic oxide and an electrolyte solution into the at least one electrolytic cell, such that the stannic oxide directly contacts the cathode or the metallic tin on the cathode; initiating electrolysis, where at the anode, an electrochemical oxidation reaction occurs to dissolve a soluble anode metal or allow evolution of chlorine and/or oxygen at an insoluble anode, and at the cathode, the stannic oxide undergoes an electrochemical reduction reaction to produce the metallic tin; and collecting the metallic tin produced from the electrolysis and/or a solid product and/or a solution product of a tin compound produced from a reaction of the metallic tin with the electrolyte solution.

What is claimed is: 
     
         1 . A process for reducing stannic oxide into metallic tin, comprising following steps:
 step 1, establishing at least one electrolytic cell provided with an anode and a cathode;   connecting the anode to a positive terminal of an electrolytic power supply, and connecting the cathode to a negative terminal of the electrolytic power supply; and feeding the stannic oxide and an electrolyte solution into the at least one electrolytic cell, such that the stannic oxide directly contacts the cathode or the metallic tin on the cathode during electrolysis;   step 2, turning on the electrolytic power supply to initiate the electrolysis, wherein at the anode, an electrochemical oxidation reaction occurs to dissolve a soluble anode metal or allow evolution of chlorine and/or oxygen at an insoluble anode, and at the cathode, the stannic oxide in direct contact with the cathode and/or the stannic oxide in direct contact with the metallic tin on the cathode undergoes an electrochemical reduction reaction to produce the metallic tin; and   step 3, collecting the metallic tin produced from the electrolysis and/or a solid product and/or a solution product of a tin compound produced from a reaction of the metallic tin with the electrolyte solution.   
     
     
         2 . The process for reducing stannic oxide into metallic tin according to  claim 1 , wherein in the step 1, the electrolyte solution is an aqueous solution comprising an organic and/or inorganic soluble electrolyte, and the organic and/or inorganic soluble electrolyte is at least one selected from the group consisting of an organic and/or inorganic soluble salt, an organic and/or inorganic soluble acid, and an organic and/or inorganic soluble alkali. 
     
     
         3 . The process for reducing stannic oxide into metallic tin according to  claim 2 , wherein the soluble salt for the organic and/or inorganic soluble electrolyte is one or a combination of two or more selected from the group consisting of a sodium salt, a potassium salt, and an ammonium salt; the soluble acid for the organic and/or inorganic soluble electrolyte is one or a combination of two or more selected from the group consisting of hydrochloric acid, sulfuric acid, and nitric acid; and the soluble alkali for the organic and/or inorganic soluble electrolyte is one or a combination of two or more selected from the group consisting of sodium hydroxide, sodium carbonate, sodium bicarbonate, potassium hydroxide, potassium carbonate, potassium bicarbonate, ammonium hydroxide, ammonium carbonate, and ammonium bicarbonate. 
     
     
         4 . The process for reducing stannic oxide into metallic tin according to  claim 1 , wherein in the step 1, the at least one electrolytic cell refers to an electrolytic cell without a separator, or an electrolytic cell provided with the separator to divide the electrolytic cell into an anode compartment and a cathode compartment, or the electrolytic cell without the separator and the electrolytic cell with the separator; the separator for the electrolytic cell is a material capable of effectively blocking electrolytically generated bubbles and the stannic oxide; and when the electrolytic cell with the separator is adopted, the stannic oxide is fed into the cathode compartment and allowed to directly contact the cathode or the metallic tin on the cathode for electrification. 
     
     
         5 . The process for reducing stannic oxide into metallic tin according to  claim 4 , wherein the separator is one or a laminated combination of two or more selected from the group consisting of a cation-exchange membrane, an anion-exchange membrane, a bipolar membrane, a reverse osmosis membrane, a non-ion-selective filter membrane, a proton-exchange membrane, and a filter cloth. 
     
     
         6 . The process for reducing stannic oxide into metallic tin according to  claim 1 , wherein in the step 1, the anode in the at least one electrolytic cell is the insoluble anode. 
     
     
         7 . The process for reducing stannic oxide into metallic tin according to  claim 1 , wherein in the step 1, the stannic oxide and the electrolyte solution are mixed to produce a slurry and then the slurry is fed into the at least one electrolytic cell, such that the stannic oxide is uniformly dispersed in the electrolyte solution; and the slurry serves as an ion exchange channel, and facilitates an increased amount of a stannic oxide powder to directly contact the cathode of the at least one electrolytic cell for energization. 
     
     
         8 . The process for reducing stannic oxide into metallic tin according to  claim 1 , further comprising: producing a soluble stannic salt and/or a stannous compound through a reaction with the electrolyte solution during the electrolysis or producing at least one selected from the group consisting of a stannous salt, stannous hydroxide, and metallic tin through a conventional chemical reaction to obtain a raw material recycled for production. 
     
     
         9 . An apparatus for reducing stannic oxide into metallic tin to implement the process according to  claim 1 , comprising at least one electrolytic cell provided with an anode and a cathode, wherein the anode is connected to a positive terminal of an electrolytic power supply, and the cathode is connected to a negative terminal of the electrolytic power supply; and during electrolysis, the cathode or the metallic tin on the cathode is in direct contact with the stannic oxide. 
     
     
         10 . The apparatus for reducing stannic oxide into metallic tin according to  claim 9 , wherein the at least one electrolytic cell is an inclined electrolytic cell, and the cathode is arranged at a low position in the inclined electrolytic cell; and under a gravity action, a stannic oxide powder accumulates around the cathode, and is in direct contact with the cathode or the metallic tin on the cathode for energization to allow an electrochemical reaction. 
     
     
         11 . The apparatus for reducing stannic oxide into metallic tin according to  claim 9 , wherein the cathode in the at least one electrolytic cell is a cathode conductive carrier; the cathode conductive carrier is a planar, spoon-shaped, or grooved cathode structure capable of loading a stannic oxide powder; the cathode conductive carrier is an electrically-conductive material or a combination of an electrically-conductive material and an electrically-insulating material; a part or all of a contact surface of the cathode conductive carrier with the loaded stannic oxide is the electrically-conductive material electrically connected to the negative terminal of the electrolytic power supply; and there is one or more connection points on the negative terminal of the electrolytic power supply for an electrical connection of the cathode conductive carrier to the negative terminal of the electrolytic power supply. 
     
     
         12 . The apparatus for reducing stannic oxide into metallic tin according to  claim 11 , wherein when the cathode conductive carrier is the combination of the electrically-conductive material and the electrically-insulating material, an inner bottom and/or an inner side of the cathode conductive carrier is the electrically-conductive material electrically connected to the negative terminal of the electrolytic power supply, and/or the electrically-conductive material electrically connected to the negative terminal of the electrolytic power supply is provided in a groove of the cathode conductive carrier, and a remaining part is the electrically-insulating material and/or the electrically-conductive material coated with the electrically-insulating material, such that the loaded stannic oxide powder is in direct contact with the inner bottom and/or the inner side of the cathode conductive carrier and/or the electrically-conductive material in the groove of the cathode conductive carrier to allow an electrochemical reduction reaction. 
     
     
         13 . The apparatus for reducing stannic oxide into metallic tin according to  claim 9 , wherein the cathode is enclosed by a filter cloth bag and/or a filter plate to confine the stannic oxide within a vicinity of the cathode to increase a contact rate of the stannic oxide with the cathode. 
     
     
         14 . The apparatus for reducing stannic oxide into metallic tin according to  claim 9 , wherein the at least one electrolytic cell is a vertical electrolytic cell, that is, the cathode is arranged below at least one anode in the at least one electrolytic cell; and the at least one electrolytic cell is an electrolytic cell without a separator and/or an electrolytic cell with a separator. 
     
     
         15 . The apparatus for reducing stannic oxide into metallic tin according to  claim 14 , wherein when a vertical electrolytic cell with the separator is adopted, the separator at a side of the cathode compartment that faces the anode and an inclined cover plate separator-fixing frame constitute a movable inclined cover plate separator; holes in the inclined cover plate separator-fixing frame are blocked with the separator; and an upper part in the cathode compartment is further provided with an outlet configured to discharge a gas or a gas and a liquid. 
     
     
         16 . The apparatus for reducing stannic oxide into metallic tin according to  claim 15 , wherein the separator is a filter cloth. 
     
     
         17 . The apparatus for reducing stannic oxide into metallic tin according to  claim 14 , wherein when both a separator-free vertical electrolytic cell and a cathode conductive carrier are adopted, the cathode conductive carrier is provided with a groove, a bottom of the groove is designed as a funnel-shaped structure provided with a liquid outlet pipe, and a filter medium is filled in the liquid outlet pipe. 
     
     
         18 . The apparatus for reducing stannic oxide into metallic tin according to  claim 17 , wherein an inner wall of the funnel-shaped structure of the bottom of the groove of the cathode conductive carrier is provided with pits configured to guide a sucked hydrogen-containing electrolyte.