Arsenic-calcium slag harmless treatment method

Abstract

The invention provides an arsenic-calcium slag harmless treatment method which comprises the following steps: obtaining arsenic-calcium slag and pyrite, inputting the arsenic-calcium slag and pyrite into a mixer for mixing, and outputting a mixed material; a mixed material is obtained and input into a medium-temperature volatilization furnace through a material inlet of the volatilization furnace, medium-temperature heating is conducted on the mixed material, first tail gas containing arsenic oxide is output through a gas outlet of the volatilization furnace, and first tailings containing calcium arsenate and pyrite are output through a tailings outlet of the volatilization furnace; obtaining first tailings, inputting the first tailings into a high-temperature decomposition furnace through a material inlet of the decomposition furnace, performing high-temperature heating on the first tailings, outputting second tail gas containing arsenic oxide and sulfur dioxide through a gas outlet of the decomposition furnace, and outputting second tailings containing calcium oxide and ferroferric oxide through a tailings outlet of the decomposition furnace; and the first tail gas and the second tail gas are obtained and input into a tail gas purification device. According to the harmless treatment method for the arsenic-calcium slag, the second tailings do not contain arsenic, and arsenic pollution is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of solid waste treatment, and in particular to a method for harmlessly treating arsenic-calcium slag. Background Art

[0002] Arsenic calcium slag contains calcium arsenate and arsenic oxide. In order to avoid the risk of environmental arsenic pollution caused by the release of arsenic in arsenic calcium slag, arsenic calcium slag needs to be further stabilized. At present, the stabilization treatment method of arsenic calcium slag is mainly cement solidification stabilization technology. Cement solidification stabilization technology mainly solidifies arsenic calcium slag and cement to improve the stabilization of arsenic calcium slag. However, this technology not only produces a large amount of secondary arsenic-containing solid waste, but also has the problem of high cost. In addition, iron arsenic co-precipitation technology can also be used for the stabilization treatment of arsenic calcium slag. This method uses a large amount of iron salts to solidify arsenic through co-precipitation and adsorption mechanisms, and finally forms arsenic into iron arsenate. However, this method uses a large amount of iron salts, and the molar ratio of iron to arsenic needs to reach more than 14, which not only increases the cost of solid arsenic, but also leads to an increase in the amount of slag, resulting in secondary pollution.

[0003] Therefore, it is necessary to provide a harmless treatment method for arsenic-calcium slag to solve the above technical problems. Summary of the invention

[0004] The invention provides a harmless treatment method for arsenic-calcium slag, wherein the tailings finally obtained do not contain arsenic, thereby avoiding arsenic pollution, and simultaneously improving the utilization rate of pyrite, saving cost and heat.

[0005] The technical solution of the present invention is:

[0006] A method for harmless treatment of arsenic calcium slag, wherein the arsenic calcium slag contains calcium arsenate and arsenic oxide, and an arsenic calcium slag harmless treatment device is used to treat the arsenic calcium slag, and the arsenic calcium slag harmless treatment device comprises:

[0007] A mixer, which is provided with a mixing inlet and a mixing outlet;

[0008] A medium-temperature volatilization furnace is provided with a volatilization furnace material inlet, a volatilization furnace gas inlet, a volatilization furnace gas outlet and a volatilization furnace tailings outlet; the volatilization furnace material inlet is connected to the mixing outlet;

[0009] A high-temperature decomposition furnace is provided with a decomposition furnace material inlet, a decomposition furnace gas inlet, a decomposition furnace gas outlet and a decomposition furnace tailings outlet; the decomposition furnace material inlet is connected to the volatilization furnace tailings outlet; and,

[0010] An exhaust gas purification device, which is provided with a purification inlet and a purification outlet, wherein the purification inlet is connected to both the volatilization furnace gas outlet and the decomposition furnace gas outlet;

[0011] The harmless treatment method for arsenic-calcium slag comprises:

[0012] S11, obtaining arsenic calcium slag and pyrite, inputting the two into the mixer through the mixing inlet, mixing the arsenic calcium slag and pyrite, and outputting the mixed material through the mixing outlet;

[0013] S12, obtaining a mixed material, inputting it into the medium-temperature volatilization furnace through the material inlet of the volatilization furnace, inputting nitrogen into the medium-temperature volatilization furnace through the gas inlet of the volatilization furnace, heating the mixed material at medium temperature, outputting a first tail gas containing arsenic oxide through the gas outlet of the volatilization furnace, and outputting a first tailing containing calcium arsenate and pyrite through the tailing outlet of the volatilization furnace;

[0014] S13, obtaining a first tailing, inputting it into the high-temperature decomposition furnace through the decomposition furnace material inlet, inputting air into the high-temperature decomposition furnace through the decomposition furnace gas inlet, heating the first tailing at high temperature, outputting a second tail gas containing arsenic oxide and sulfur dioxide through the decomposition furnace gas outlet, and outputting a second tailing containing calcium oxide and ferrosoferric oxide through the decomposition furnace tailing outlet; and,

[0015] S14, obtaining the first tail gas and the second tail gas, inputting the first tail gas and the second tail gas into the tail gas purification device through the purification inlet, and discharging the purified tail gas through the purification outlet.

[0016] In the harmless treatment method for arsenic-calcium slag described in the present invention, in step S12, the heating temperature is 550° C.-600° C., and the heating time is 60 min-90 min.

[0017] In the harmless treatment method for arsenic-calcium slag described in the present invention, in step S13, the heating temperature is 800° C.-850° C., and the heating time is 60 min-90 min.

[0018] In the harmless treatment method for arsenic-calcium slag described in the present invention, calcium arsenate accounts for 70%-80% of the mass of the arsenic-calcium slag; in step S13, the air introduced into the high-temperature decomposition furnace has oxygen accounting for 50%-60% of the mass of the arsenic-calcium slag; in step S11, the pyrite input into the mixer has ferrous disulfide accounting for 90%-100% of the mass of the arsenic-calcium slag.

[0019] In the harmless treatment method of arsenic-calcium slag described in the present invention, the harmless treatment equipment of arsenic-calcium slag also includes a paddle-type preheating feeder, whose inner shell is provided with a feeder material inlet, a feeder gas outlet and a feeder material outlet; the feeder material inlet is connected to the mixing outlet; the feeder material outlet is connected to the volatilization furnace material inlet;

[0020] The harmless treatment method of arsenic-calcium slag also includes step S15, obtaining a mixed material, inputting it into the paddle-type preheating feeder through the material inlet of the feeder, heating the mixed material, the heating temperature is 150°C-200°C, the heating time is 60min-120min, and water vapor is discharged through the gas outlet of the feeder, and the dehydrated mixed material is output through the material outlet of the feeder; step S15 is located after step S11 and before step S12.

[0021] In the harmless treatment method for arsenic-calcium slag of the present invention, the harmless treatment equipment for arsenic-calcium slag further comprises:

[0022] A high-temperature gas-solid separator is provided with a separator inlet, a separator solid outlet and a separator gas outlet; the separator inlet is connected to both the volatilization furnace gas outlet and the decomposition furnace gas outlet; and,

[0023] A condensation arsenic collection chamber is provided with an arsenic collection chamber inlet and an arsenic collection chamber gas outlet; the arsenic collection chamber inlet is connected to the separator gas outlet; the arsenic collection chamber gas outlet is connected to the purification inlet;

[0024] The harmless treatment method for arsenic-calcium slag also includes the following steps:

[0025] S16, obtaining a first tail gas and a second tail gas, inputting the two into the high-temperature gas-solid separator through the separator inlet, outputting impurities through the separator solid outlet, and outputting a third tail gas containing arsenic oxide and sulfur dioxide through the separator gas outlet; and,

[0026] S17, obtaining the third tail gas, inputting it into the condensation arsenic collecting chamber through the inlet of the arsenic collecting chamber to collect refined white arsenic, and outputting the fourth tail gas containing sulfur dioxide through the gas outlet of the arsenic collecting chamber;

[0027] Step S16 and step S17 are located after step S13 and before step S14; step S14 is to obtain the fourth exhaust gas and input the fourth exhaust gas into the exhaust gas purification device for treatment.

[0028] In the harmless treatment method of arsenic-calcium slag of the present invention, the harmless treatment equipment of arsenic-calcium slag further comprises a condenser, which is provided with a condensation inlet and a condensation outlet, and the condensation inlet is connected to the gas outlet of the feeder;

[0029] The harmless treatment method for arsenic-calcium slag also includes step S18, obtaining water vapor, inputting it into the condenser through the condensation inlet, then outputting wastewater through the condensation outlet, and transporting the wastewater to a sewage treatment plant; step S18 is located after step S15.

[0030] In the harmless treatment method of arsenic-calcium slag of the present invention, the harmless treatment equipment of arsenic-calcium slag further comprises a discharge heat exchanger, the inner tank of the discharge heat exchanger is provided with a heat exchanger material inlet and a heat exchanger material outlet; the heat exchanger material inlet is connected to the decomposition furnace tailings outlet;

[0031] The harmless treatment method for arsenic-calcium slag also includes step S19, obtaining second tailings, inputting them into the discharging heat exchanger through the material inlet of the heat exchanger, cooling the second tailings, and outputting the cooled second tailings through the material outlet of the heat exchanger; step S19 is located after step S13.

[0032] In the harmless treatment method of arsenic-calcium slag of the present invention, the outer tank of the paddle-type preheating feeder is also provided with a feeder hot oil inlet and a feeder cold oil outlet; the outer tank of the discharge heat exchanger is also provided with a heat exchanger cold oil inlet and a heat exchanger hot oil outlet; the heat exchanger hot oil outlet is connected to the feeder hot oil inlet;

[0033] In step S19, cold heat transfer oil is input into the outer tank of the discharging heat exchanger through the cold oil inlet of the heat exchanger to cool the second tailings, and the hot heat transfer oil is output through the hot oil outlet of the heat exchanger; the arsenic-calcium slag harmless treatment method also includes step S20, obtaining the hot heat transfer oil output from the hot oil outlet of the heat exchanger, and inputting it into the outer tank of the paddle-type preheating feeder through the hot oil inlet of the feeder; step S20 is located after step S19; in step S15, cold heat transfer oil is output through the cold oil outlet of the feeder.

[0034] In the harmless treatment method of arsenic-calcium slag described in the present invention, the cold oil inlet of the heat exchanger is connected to the cold oil outlet of the feeder; the harmless treatment method of arsenic-calcium slag also includes step S21, obtaining the cold heat transfer oil output from the cold oil outlet of the feeder, and inputting it into the outer tank of the discharge heat exchanger through the cold oil inlet of the heat exchanger.

[0035] Compared with the prior art, the present invention has the following beneficial effects: the harmless treatment method for arsenic calcium slag of the present invention first mixes the arsenic calcium slag and pyrite in a mixer to ensure sufficient subsequent reaction; then the mixed material containing the arsenic calcium slag and pyrite is input into a medium-temperature volatilization furnace to make the arsenic oxide in the mixed material gaseous and separated from the first tailings containing calcium arsenate and pyrite; the medium-temperature volatilization furnace is a nitrogen atmosphere, which can avoid the arsenic oxide from reacting with oxygen to generate solid arsenic pentoxide, which increases the difficulty of subsequent treatment; then the first tailings is input into a high-temperature decomposition furnace, and the calcium arsenate and pyrite in the first tailings react chemically in an oxygen atmosphere, so that the arsenic exists in the form of gaseous arsenic oxide, which is separated from the second tailings containing calcium oxide and ferroferric oxide; the second tailings finally obtained do not contain arsenic, and the first tail gas and the second tail gas are treated by a tail gas purification device to avoid arsenic pollution. At the same time, the ore is first subjected to medium-temperature treatment in a medium-temperature volatilization furnace and then subjected to high-temperature treatment in a high-temperature decomposition furnace, so that the pyrite in the medium-temperature volatilization furnace will not react with arsenic oxide, and all the pyrite reacts with calcium arsenate in the high-temperature decomposition furnace, thereby improving the utilization rate of the pyrite and saving costs; the arsenic oxide in the arsenic-calcium slag is first converted into gaseous form and discharged in the medium-temperature volatilization furnace, so that the arsenic-calcium slag in the high-temperature decomposition furnace is only calcium arsenate, and the treatment time in the high-temperature decomposition furnace can also be shortened, saving heat. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. The drawings described below are only drawings corresponding to some embodiments of the present invention.

[0037] Figure 1 A schematic structural diagram of an arsenic-calcium slag harmless treatment device provided for a preferred embodiment of the invention.

[0038] Figure 2 A partial flow chart of the method for harmless treatment of arsenic-calcium slag provided for a preferred embodiment of the invention.

[0039] Figure 3 Another partial flow chart of the method for harmless treatment of arsenic-calcium slag provided for a preferred embodiment of the invention.

[0040] in,

[0041] 11. Mixing machine, 111. Mixing inlet, 112. Mixing outlet,

[0042] 12. Medium temperature volatilization furnace, 121. Material inlet of volatilization furnace, 122. Gas inlet of volatilization furnace, 123. Gas outlet of volatilization furnace, 124. Tailing outlet of volatilization furnace,

[0043] 13. High temperature decomposition furnace, 131. Decomposition furnace material inlet, 132. Decomposition furnace gas inlet, 133. Decomposition furnace gas outlet, 134. Decomposition furnace tailings outlet,

[0044] 14. Exhaust gas purification device, 141. Purification inlet, 142. Purification outlet,

[0045] 15. Paddle preheating feeder, 151. Feeder material inlet, 152. Feeder gas outlet, 153. Feeder material outlet, 154. Feeder hot oil inlet, 155. Feeder cold oil outlet,

[0046] 16. High temperature gas-solid separator, 161. Separator inlet, 162. Separator solid outlet, 163. Separator gas outlet,

[0047] 17. Condensation arsenic collection chamber, 171. Arsenic collection chamber entrance, 172. Arsenic collection chamber gas outlet,

[0048] 18. Discharging heat exchanger, 181. Heat exchanger material inlet, 182. Heat exchanger material outlet, 183. Heat exchanger cold oil inlet, 184. Heat exchanger hot oil outlet,

[0049] 19. condenser, 191. condensation inlet, 192. condensation outlet.

[0050] In the figures, structurally similar elements are denoted by the same reference numerals. DETAILED DESCRIPTION

[0051] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0052] The directional terms mentioned in the present invention, such as "up", "down", "front", "back", "left", "right", "inside", "outside", "side", "top" and "bottom", are only for reference to the orientation of the drawings. The directional terms used are used to illustrate and understand the present invention, but not to limit the present invention.

[0053] The terms "first", "second", etc. in the present invention are used for descriptive purposes only and should not be understood as indicating or implying relative importance, and should not be used as a limitation on the order of precedence.

[0054] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0055] Arsenic calcium slag contains calcium arsenate and arsenic oxide. In order to avoid the risk of environmental arsenic pollution caused by the release of arsenic in arsenic calcium slag, arsenic calcium slag needs to be further stabilized. At present, the stabilization treatment method of arsenic calcium slag is mainly cement solidification stabilization technology. Cement solidification stabilization technology mainly solidifies arsenic calcium slag and cement to improve the stabilization of arsenic calcium slag. However, this technology not only produces a large amount of secondary arsenic-containing solid waste, but also has the problem of high cost. In addition, iron arsenic co-precipitation technology can also be used for the stabilization treatment of arsenic calcium slag. This method uses a large amount of iron salts to solidify arsenic through co-precipitation and adsorption mechanisms, and finally forms arsenic into iron arsenate. However, this method uses a large amount of iron salts, and the molar ratio of iron to arsenic needs to reach more than 14, which not only increases the cost of solid arsenic, but also leads to an increase in the amount of slag, resulting in secondary pollution.

[0056] The following is a preferred embodiment of a harmless treatment method for arsenic-calcium slag provided by the present invention that can solve the above technical problems.

[0057] Please refer to Figure 1 , Figure 2 and Figure 3 The preferred embodiment of the present invention provides a harmless treatment method for arsenic calcium slag, wherein the arsenic calcium slag contains calcium arsenate and arsenic oxide, and the arsenic calcium slag harmless treatment equipment is used to treat the arsenic calcium slag, and the arsenic calcium slag harmless treatment equipment includes a mixer 11, a medium-temperature volatilization furnace 12, a high-temperature decomposition furnace 13 and a tail gas purification device 14. The mixer 11 is provided with a mixing inlet 111 and a mixing outlet 112. The medium-temperature volatilization furnace 12 is provided with a volatilization furnace material inlet 121, a volatilization furnace gas inlet 122, a volatilization furnace gas outlet 123 and a volatilization furnace tail slag outlet 124. The volatilization furnace material inlet 121 is connected to the mixing outlet 112. The high-temperature decomposition furnace 13 is provided with a decomposition furnace material inlet 131, a decomposition furnace gas inlet 132, a decomposition furnace gas outlet 133 and a decomposition furnace tail slag outlet 134. The decomposition furnace material inlet 131 is connected to the volatilization furnace tail slag outlet 124. The tail gas purification device 14 is provided with a purification inlet 141 and a purification outlet 142 , and the purification inlet 141 is connected to both the volatilization furnace gas outlet 123 and the decomposition furnace gas outlet 133 .

[0058] The harmless treatment methods of arsenic-calcium slag include:

[0059] S11, obtaining arsenic calcium slag and pyrite, inputting the two into the mixer 11 through the mixing inlet 111, mixing the arsenic calcium slag and pyrite, and outputting the mixed material through the mixing outlet 112;

[0060] S12, obtaining a mixed material, inputting it into a medium-temperature volatilization furnace 12 through a volatilization furnace material inlet 121, and inputting nitrogen into the medium-temperature volatilization furnace 12 through a volatilization furnace gas inlet 122, heating the mixed material at a medium temperature, outputting a first tail gas containing arsenic oxide through a volatilization furnace gas outlet 123, and outputting a first tailing containing calcium arsenate and pyrite through a volatilization furnace tailing outlet 124;

[0061] S13, obtaining the first tailings, inputting them into the high-temperature decomposition furnace 13 through the decomposition furnace material inlet 131, and inputting air into the high-temperature decomposition furnace 13 through the decomposition furnace gas inlet 132, heating the first tailings at high temperature, outputting the second tail gas containing arsenic oxide and sulfur dioxide through the decomposition furnace gas outlet 133, and outputting the second tailings containing calcium oxide and ferroferric oxide through the decomposition furnace tailing outlet 134; the reaction chemical formula of calcium arsenate and pyrite is:

[0062] Ca3(AsO4)2+3FeS2+7O2(g)=As2O3(g)+3CaO+6SO2(g)+Fe3O4;

[0063] S14 , obtaining the first tail gas and the second tail gas, inputting the two into the tail gas purification device 14 through the purification inlet 141 , and discharging the purified tail gas through the purification outlet 142 .

[0064] The harmless treatment method of arsenic calcium slag of the present invention comprises the following steps: firstly, the arsenic calcium slag and pyrite are mixed in a mixer 11 to ensure sufficient subsequent reaction; then, the mixed material containing the arsenic calcium slag and pyrite is input into a medium-temperature volatilization furnace 12 to make the arsenic oxide in the mixed material gaseous and separated from the first tailings containing calcium arsenate and pyrite; the medium-temperature volatilization furnace 12 is in a nitrogen atmosphere to avoid the arsenic oxide from reacting with oxygen to generate solid arsenic pentoxide, which increases the difficulty of subsequent treatment; then, the first tailings is input into a high-temperature decomposition furnace 13; in an oxygen atmosphere, the calcium arsenate and pyrite in the first tailings chemically react to make the arsenic exist in the form of gaseous arsenic oxide, which is separated from the second tailings containing calcium oxide and ferroferric oxide; the second tailings finally obtained do not contain arsenic; and the first tail gas and the second tail gas are treated by a tail gas purification device 14 to avoid arsenic pollution. At the same time, the arsenic is first treated at a medium temperature in the medium temperature volatilization furnace 12 and then treated at a high temperature in the high temperature decomposition furnace 13, so that the pyrite in the medium temperature volatilization furnace 12 will not react with arsenic oxide, and all the pyrite reacts with calcium arsenate in the high temperature decomposition furnace 13, thereby improving the utilization rate of the pyrite and saving costs; the arsenic oxide in the arsenic calcium slag is first converted into gaseous form and discharged in the medium temperature volatilization furnace 12, so that the arsenic calcium slag in the high temperature decomposition furnace 13 is only calcium arsenate, and the processing time in the high temperature decomposition furnace 13 can also be shortened, saving heat.

[0065] The heating temperature is 550°C-600°C and the heating time is 60min-90min, which can fully convert arsenic oxide into gas without causing arsenic oxide to react with pyrite.

[0066] The heating temperature is 800°C-850°C and the heating time is 60min-90min, which can make calcium arsenate and pyrite react fully without causing heat waste.

[0067] Calcium arsenate is 70%-80% of the mass of the calcium arsenate slag; in step S13, the oxygen in the air introduced into the high-temperature decomposition furnace 13 is 50%-60% of the mass of the calcium arsenate slag, which not only meets the requirements of the reaction between calcium arsenate and pyrite, but also avoids excessive oxygen, resulting in the reaction of arsenic oxide and oxygen to generate solid arsenic pentoxide. In step S11, the pyrite input into the mixer 11 has ferrous disulfide of 90%-100% of the mass of the calcium arsenate slag, so that the pyrite meets the requirements of the decomposition of calcium arsenate, while not wasting pyrite and not increasing the amount of the second tailings.

[0068] The arsenic-calcium slag harmless treatment equipment also includes a paddle-type preheating feeder 15, whose inner shell is provided with a feeder material inlet 151, a feeder gas outlet 152 and a feeder material outlet 153. The feeder material inlet 151 is connected to the mixing outlet 112; the feeder material outlet 153 is connected to the volatilization furnace material inlet 121.

[0069] The harmless treatment method of arsenic-calcium slag also includes step S15, obtaining a mixed material, inputting it into a paddle-type preheating feeder 15 through a feeder material inlet 151, heating the mixed material, the heating temperature is 150°C-200°C, the heating time is 60min-120min, and water vapor is discharged through a feeder gas outlet 152, and the dehydrated mixed material is output through a feeder material outlet 153; step S15 is located after step S11 and before step S12. In the above steps, the water in the mixed material can be converted into water vapor and discharged through the paddle-type preheating feeder 15, thereby improving the processing efficiency of the subsequent medium-temperature volatilization furnace 12. The temperature of the paddle-type preheating feeder 15 is much lower than that of the medium-temperature volatilization furnace 12, thus saving heat.

[0070] The arsenic-calcium slag harmless treatment equipment also includes a high-temperature gas-solid separator 16 and a condensation arsenic collection chamber 17 .

[0071] The high-temperature gas-solid separator 16 is provided with a separator inlet 161 , a separator solid outlet 162 and a separator gas outlet 163 ; the separator inlet 161 is connected to both the volatilization furnace gas outlet 123 and the decomposition furnace gas outlet 133 .

[0072] The condensation arsenic collecting chamber 17 is provided with an arsenic collecting chamber inlet 171 and an arsenic collecting chamber gas outlet 172 ; the arsenic collecting chamber inlet 171 is connected to the separator gas outlet 163 ; and the arsenic collecting chamber gas outlet 172 is connected to the purification inlet 141 .

[0073] The method for harmless treatment of arsenic-calcium slag also includes the following steps:

[0074] S16, obtaining the first tail gas and the second tail gas, inputting the two into the high-temperature gas-solid separator 16 through the separator inlet 161, outputting impurities through the separator solid outlet 162, and outputting the third tail gas containing arsenic oxide and sulfur dioxide through the separator gas outlet 163; and,

[0075] S17, obtaining the third tail gas, inputting it into the condensation arsenic collecting chamber 17 through the arsenic collecting chamber inlet 171 to collect the refined white arsenic, and outputting the fourth tail gas containing sulfur dioxide through the arsenic collecting chamber gas outlet 172;

[0076] Step S16 and step S17 are located after step S13 and before step S14; step S14 is to obtain the fourth exhaust gas and input the fourth exhaust gas into the exhaust gas purification device 14 for processing.

[0077] In the above steps, the high-temperature gas-solid separator 16 allows arsenic oxide and sulfur dioxide to continue to remain in a gaseous state at a high temperature, and the solid impurities are filtered out through the membrane tube of the high-temperature gas-solid separator 16, and the third tail gas containing arsenic oxide and sulfur dioxide and no impurities is output through the separator gas outlet 163, and then enters the condensation arsenic collection chamber 17. The condensation arsenic collection chamber 17 allows sulfur dioxide to continue to remain in a gaseous state, and its low temperature environment allows arsenic trioxide to become a solid powder, which can be collected to obtain refined white arsenic, thereby improving resource utilization.

[0078] The arsenic-calcium slag harmless treatment equipment also includes a condenser 19 , which is provided with a condensation inlet 191 and a condensation outlet 192 , and the condensation inlet 191 is connected to the feeder gas outlet 152 .

[0079] The harmless treatment method of arsenic-calcium slag also includes step S18, obtaining water vapor, inputting it into the condenser 19 through the condensation inlet 191, and then outputting wastewater through the condensation outlet 192, and transporting the wastewater to the sewage treatment plant; step S18 is located after step S15. In the above steps, the water vapor can be converted into liquid water through the condenser 19, which is convenient for transporting to the sewage treatment plant for treatment to avoid environmental pollution.

[0080] The arsenic-calcium slag harmless treatment equipment also includes a discharge heat exchanger 18 , the inner tank of which is provided with a heat exchanger material inlet 181 and a heat exchanger material outlet 182 ; the heat exchanger material inlet 181 is connected to the decomposition furnace tail slag outlet 134 .

[0081] The harmless treatment method of arsenic-calcium slag also includes step S19, obtaining the second tailings, inputting them into the discharging heat exchanger 18 through the heat exchanger material inlet 181, cooling the second tailings, and outputting the cooled second tailings through the heat exchanger material outlet 182; step S19 is located after step S13. In the above steps, the second tailings are cooled by the discharging heat exchanger 18, so that the second tailings can be piled up and stored.

[0082] The outer shell of the paddle preheating feeder 15 is also provided with a feeder hot oil inlet 154 and a feeder cold oil outlet 155; the outer shell of the discharge heat exchanger 18 is also provided with a heat exchanger cold oil inlet 183 and a heat exchanger hot oil outlet 184; the heat exchanger hot oil outlet 184 is connected to the feeder hot oil inlet 154.

[0083] In step S19, cold heat transfer oil is input into the outer tank of the discharge heat exchanger 18 through the cold oil inlet 183 of the heat exchanger to cool the second tailings, and the hot heat transfer oil is output through the hot oil outlet 184 of the heat exchanger; the arsenic-calcium slag harmless treatment method also includes step S20, obtaining the hot heat transfer oil output from the hot oil outlet 184 of the heat exchanger, and inputting it into the outer tank of the paddle-type preheating feeder 15 through the hot oil inlet 154 of the feeder; step S20 is located after step S19; in step S15, the cold heat transfer oil is output through the cold oil outlet 155 of the feeder.

[0084] The high-temperature second tailings in the inner tank of the discharge heat exchanger 18 will transfer heat to the heat transfer oil in the outer tank of the discharge heat exchanger 18. In the above steps, the hot heat transfer oil output from the heat exchanger hot oil outlet 184 is transported to the outer tank of the paddle-type preheating feeder 15 through the feeder hot oil inlet 154, which can provide a heat source to heat the mixed material in the inner tank of the paddle-type preheating feeder 15, effectively saving and utilizing heat.

[0085] The heat exchanger cold oil inlet 183 is connected to the feeder cold oil outlet 155; the arsenic-calcium slag harmless treatment method also includes step S21, obtaining the cold heat transfer oil output by the feeder cold oil outlet 155, and inputting it into the outer tank of the discharge heat exchanger 18 through the heat exchanger cold oil inlet 183.

[0086] The heat of the heat transfer oil in the outer tank of the paddle-type preheating feeder 15 is transferred to the first mixture in the inner tank of the paddle-type preheating feeder 15. In the above steps, the cold heat transfer oil output from the cold oil outlet 155 of the feeder is input into the outer tank of the discharge heat exchanger 18 through the cold oil inlet 183 of the heat exchanger, which can effectively cool the second tailings.

[0087] The harmless treatment method of arsenic-calcium slag according to the preferred embodiment of the present invention:

[0088] Obtain arsenic calcium slag and pyrite, input the two into the mixer 11 through the mixing inlet 111, mix the arsenic calcium slag and pyrite, and output the mixed material through the mixing outlet 112;

[0089] Obtain the mixed material, input it into the paddle preheating feeder 15 through the feeder material inlet 151, heat the mixed material at a heating temperature of 150° C.-200° C. for 60 min-120 min, discharge water vapor through the feeder gas outlet 152, and output the dehydrated mixed material through the feeder material outlet 153;

[0090] Obtain the dehydrated mixed material, input it into the medium-temperature volatilization furnace 12 through the volatilization furnace material inlet 121, input nitrogen into the medium-temperature volatilization furnace 12 through the volatilization furnace gas inlet 122, heat the mixed material at medium temperature, output the first tail gas containing arsenic oxide through the volatilization furnace gas outlet 123, and output the first tailings containing calcium arsenate and pyrite through the volatilization furnace tailings outlet 124;

[0091] Obtaining a first tailing, inputting it into a high-temperature decomposition furnace 13 through a decomposition furnace material inlet 131, inputting air into the high-temperature decomposition furnace 13 through a decomposition furnace gas inlet 132, heating the first tailing at high temperature, outputting a second tail gas containing arsenic oxide and sulfur dioxide through a decomposition furnace gas outlet 133, and outputting a second tailing containing calcium oxide and ferrosoferric oxide through a decomposition furnace tailing outlet 134;

[0092] Obtain the second tailings, input them into the discharging heat exchanger 18 through the heat exchanger material inlet 181, cool the second tailings, and output the cooled second tailings through the heat exchanger material outlet 182;

[0093] Obtain the hot heat transfer oil output from the heat exchanger hot oil outlet 184, and input it into the outer tank of the paddle type preheating feeder 15 through the feeder hot oil inlet 154;

[0094] Obtain the cold heat transfer oil output from the cold oil outlet 155 of the feeder, and input it into the outer tank of the discharge heat exchanger 18 through the cold oil inlet 183 of the heat exchanger;

[0095] Obtaining the first tail gas and the second tail gas, inputting the two into the high-temperature gas-solid separator 16 through the separator inlet 161, outputting impurities through the separator solid outlet 162, and outputting the third tail gas containing arsenic oxide and sulfur dioxide through the separator gas outlet 163;

[0096] Obtain the third tail gas, input it into the condensation arsenic collecting chamber 17 through the arsenic collecting chamber inlet 171 to collect the refined white arsenic, and output the fourth tail gas containing sulfur dioxide through the arsenic collecting chamber gas outlet 172;

[0097] Obtaining a fourth tail gas, inputting the fourth tail gas into the tail gas purification device 14 through the purification inlet 141, and discharging the purified tail gas through the purification outlet 142;

[0098] The water vapor is obtained and input into the condenser 19 through the condensation inlet 191, and then the waste water is output through the condensation outlet 192, and the waste water is transported to the sewage treatment plant.

[0099] This is the process of the harmless treatment method of arsenic-calcium slag in this preferred embodiment.

[0100] The harmless treatment method of arsenic calcium slag of the present invention comprises the following steps: firstly mixing the arsenic calcium slag and pyrite in a mixer to ensure sufficient subsequent reaction; then inputting the mixed material containing the arsenic calcium slag and pyrite into a medium-temperature volatilization furnace to make the arsenic oxide in the mixed material become gaseous and separate from the first tailings containing calcium arsenate and pyrite; the medium-temperature volatilization furnace is in a nitrogen atmosphere, which can avoid the arsenic oxide from reacting with oxygen to generate solid arsenic pentoxide, which increases the difficulty of subsequent treatment; then inputting the first tailings into a high-temperature decomposition furnace, and in an oxygen atmosphere, the calcium arsenate and pyrite in the first tailings chemically react to make the arsenic exist in the form of gaseous arsenic oxide, which is separated from the second tailings containing calcium oxide and ferroferric oxide; the second tailings finally obtained do not contain arsenic; and the first tail gas and the second tail gas are treated by a tail gas purification device to avoid arsenic pollution. At the same time, the ore is first subjected to medium-temperature treatment in a medium-temperature volatilization furnace and then subjected to high-temperature treatment in a high-temperature decomposition furnace, so that the pyrite in the medium-temperature volatilization furnace will not react with arsenic oxide, and all the pyrite reacts with calcium arsenate in the high-temperature decomposition furnace, thereby improving the utilization rate of the pyrite and saving costs; the arsenic oxide in the arsenic-calcium slag is first converted into gaseous form and discharged in the medium-temperature volatilization furnace, so that the arsenic-calcium slag in the high-temperature decomposition furnace is only calcium arsenate, and the treatment time in the high-temperature decomposition furnace can also be shortened, saving heat.

[0101] To sum up, although the present invention has been disclosed as above in the form of preferred embodiments, the protection scope of the present invention is not limited thereto, and any technician familiar with the technical field can make equivalent substitutions or changes according to the concept of the technical solution of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for harmlessly treating arsenic calcium slag, wherein the arsenic calcium slag contains calcium arsenate and arsenic oxide. It is characterized in that Arsenic calcium slag harmless treatment equipment is used to treat the arsenic calcium slag, and the arsenic calcium slag harmless treatment equipment includes: A mixer, which is provided with a mixing inlet and a mixing outlet; A medium-temperature volatilization furnace is provided with a volatilization furnace material inlet, a volatilization furnace gas inlet, a volatilization furnace gas outlet and a volatilization furnace tailings outlet; the volatilization furnace material inlet is connected to the mixing outlet; A high-temperature decomposition furnace is provided with a decomposition furnace material inlet, a decomposition furnace gas inlet, a decomposition furnace gas outlet and a decomposition furnace tailings outlet; the decomposition furnace material inlet is connected to the volatilization furnace tailings outlet; and, An exhaust gas purification device, which is provided with a purification inlet and a purification outlet, wherein the purification inlet is connected to both the volatilization furnace gas outlet and the decomposition furnace gas outlet; The harmless treatment method for arsenic-calcium slag comprises: S11, obtaining arsenic calcium slag and pyrite, inputting the two into the mixer through the mixing inlet, mixing the arsenic calcium slag and pyrite, and outputting the mixed material through the mixing outlet; S12, obtaining a mixed material, inputting it into the medium-temperature volatilization furnace through the material inlet of the volatilization furnace, inputting nitrogen into the medium-temperature volatilization furnace through the gas inlet of the volatilization furnace, heating the mixed material at medium temperature, outputting a first tail gas containing arsenic oxide through the gas outlet of the volatilization furnace, and outputting a first tailing containing calcium arsenate and pyrite through the tailing outlet of the volatilization furnace; S13, obtaining a first tailing, inputting it into the high-temperature decomposition furnace through the decomposition furnace material inlet, inputting air into the high-temperature decomposition furnace through the decomposition furnace gas inlet, heating the first tailing at high temperature, outputting a second tail gas containing arsenic oxide and sulfur dioxide through the decomposition furnace gas outlet, and outputting a second tailing containing calcium oxide and ferrosoferric oxide through the decomposition furnace tailing outlet; and, S14, obtaining the first tail gas and the second tail gas, inputting the first tail gas and the second tail gas into the tail gas purification device through the purification inlet, and discharging the purified tail gas through the purification outlet.

2. The method for harmless treatment of arsenic-calcium slag according to claim 1, It is characterized in that In step S12, the heating temperature is 550°C-600°C, and the heating time is 60min-90min.

3. The method for harmless treatment of arsenic-calcium slag according to claim 1, It is characterized in that In step S13, the heating temperature is 800°C-850°C, and the heating time is 60min-90min.

4. The method for harmless treatment of arsenic-calcium slag according to claim 1, It is characterized in that The calcium arsenate is 70%-80% of the mass of the arsenic calcium slag; in step S13, the oxygen in the air introduced into the high-temperature decomposition furnace is 50%-60% of the mass of the arsenic calcium slag; in step S11, the pyrite input into the mixer has ferrous disulfide of 90%-100% of the mass of the arsenic calcium slag.

5. The method for harmless treatment of arsenic-calcium slag according to claim 1, It is characterized in that The arsenic-calcium slag harmless treatment equipment also includes a paddle-type preheating feeder, whose inner shell is provided with a feeder material inlet, a feeder gas outlet and a feeder material outlet; the feeder material inlet is connected to the mixing outlet; the feeder material outlet is connected to the volatilization furnace material inlet; The harmless treatment method of arsenic-calcium slag also includes step S15, obtaining a mixed material, inputting it into the paddle-type preheating feeder through the material inlet of the feeder, heating the mixed material, the heating temperature is 150°C-200°C, the heating time is 60min-120min, and water vapor is discharged through the gas outlet of the feeder, and the dehydrated mixed material is output through the material outlet of the feeder; step S15 is located after step S11 and before step S12.

6. The method for harmless treatment of arsenic-calcium slag according to claim 5, It is characterized in that The arsenic-calcium slag harmless treatment equipment also includes: A high-temperature gas-solid separator is provided with a separator inlet, a separator solid outlet and a separator gas outlet; the separator inlet is connected to both the volatilization furnace gas outlet and the decomposition furnace gas outlet; and, A condensation arsenic collection chamber is provided with an arsenic collection chamber inlet and an arsenic collection chamber gas outlet; the arsenic collection chamber inlet is connected to the separator gas outlet; the arsenic collection chamber gas outlet is connected to the purification inlet; The harmless treatment method for arsenic-calcium slag also includes the following steps: S16, obtaining a first tail gas and a second tail gas, inputting the two into the high-temperature gas-solid separator through the separator inlet, outputting impurities through the separator solid outlet, and outputting a third tail gas containing arsenic oxide and sulfur dioxide through the separator gas outlet; and, S17, obtaining the third tail gas, inputting it into the condensation arsenic collecting chamber through the inlet of the arsenic collecting chamber to collect refined white arsenic, and outputting the fourth tail gas containing sulfur dioxide through the gas outlet of the arsenic collecting chamber; Step S16 and step S17 are located after step S13 and before step S14; step S14 is to obtain the fourth exhaust gas and input the fourth exhaust gas into the exhaust gas purification device for treatment.

7. The method for harmless treatment of arsenic-calcium slag according to claim 5, It is characterized in that The arsenic-calcium slag harmless treatment equipment also includes a condenser, which is provided with a condensation inlet and a condensation outlet, and the condensation inlet is connected to the gas outlet of the feeder; The harmless treatment method for arsenic-calcium slag also includes step S18, obtaining water vapor, inputting it into the condenser through the condensation inlet, then outputting wastewater through the condensation outlet, and transporting the wastewater to a sewage treatment plant; step S18 is located after step S15.

8. The method for harmless treatment of arsenic-calcium slag according to claim 5, It is characterized in that The arsenic-calcium slag harmless treatment equipment also includes a discharge heat exchanger, the inner tank of which is provided with a heat exchanger material inlet and a heat exchanger material outlet; the heat exchanger material inlet is connected to the decomposition furnace tailings outlet; The harmless treatment method for arsenic-calcium slag also includes step S19, obtaining second tailings, inputting them into the discharging heat exchanger through the material inlet of the heat exchanger, cooling the second tailings, and outputting the cooled second tailings through the material outlet of the heat exchanger; step S19 is located after step S13.

9. The method for harmless treatment of arsenic-calcium slag according to claim 8, It is characterized in that The outer tank of the paddle-type preheating feeder is also provided with a feeder hot oil inlet and a feeder cold oil outlet; the outer tank of the discharge heat exchanger is also provided with a heat exchanger cold oil inlet and a heat exchanger hot oil outlet; the heat exchanger hot oil outlet is connected to the feeder hot oil inlet; In step S19, cold heat transfer oil is input into the outer tank of the discharging heat exchanger through the cold oil inlet of the heat exchanger to cool the second tailings, and hot heat transfer oil is output through the hot oil outlet of the heat exchanger; the arsenic-calcium slag harmless treatment method also includes step S20, obtaining the hot heat transfer oil output from the hot oil outlet of the heat exchanger, and inputting it into the outer tank of the paddle-type preheating feeder through the hot oil inlet of the feeder; Step S20 is located after step S19; in step S15, the cold heat transfer oil is output through the cold oil outlet of the feeder.

10. The method for harmless treatment of arsenic-calcium slag according to claim 9, It is characterized in that The cold oil inlet of the heat exchanger is connected to the cold oil outlet of the feeder; the arsenic-calcium slag harmless treatment method also includes step S21, obtaining the cold heat transfer oil output from the cold oil outlet of the feeder, and inputting it into the outer tank of the discharge heat exchanger through the cold oil inlet of the heat exchanger.

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