Abstract

Provided are improved device for preparing phosphoric acid from kiln egression flue gas of a phosphoric acid process of a kiln method, and a phosphoric acid preparing process. The process comprises: introducing the kiln egression flue gas that contains P2O5 and fluorine to a hydration tower (1), and before the introducing, opening an acid liquor circulation spraying system connected to the hydrated tower (1), wherein a great portion of the phosphoric acid generated in the heat and mass exchanging between the flue gas and spraying liquid is absorbed into the spraying liquid; allowing the sprayed phosphoric acid solution to circulate into the acid liquid circulation spray system finally through a liquid inlet (14); then allowing the egression flue gas from an egression flue gas outlet (12) to pass through a phosphoric acid gas scrubber (3) and an electrostatic mist precipitator (4) in sequence, so that phosphoric acid gas mixed in the egression flue gas from the hydrated tower (1) is further collected, and the concentrated phosphoric acid solution in the acid liquid circulation spray system can enter a refining process; and allowing the flue gas containing fluorine from a mist separation tower to enter a follow-up fluorine recycling processing.

IPC Classes  ?

• C01B 25/18 - Phosphoric acid

Abstract

Disclosed is a raw material pre-treatment process system suitable for a kiln phosphoric acid process, comprising a carbonaceous reductant, a phosphate ore and a silica pre-treatment system which are independent from one another, outlets of the carbonaceous reductant, phosphate ore pre-treatment system and silica pre-treatment system are all connected to an inner pellet material mixing device via a first delivery device, and outlets of the carbonaceous reductant and the silica pre-treatment system are both additionally connected to a shell material mixing device via a second delivery device. Also disclosed is a raw material pre-treatment process suitable for a kiln phosphoric acid process, i.e. pre-treating carbonaceous reductant, phosphate ore and silica respectively, feeding the carbonaceous reductant powder, phosphate ore powder and silica powder into the inner ball material mixing device for pelletizing, and feeding the carbonaceous reductant and silica into the shell material mixing device for mixing.

IPC Classes  ?

• B02C 23/38 - Adding fluid, other than for crushing or disintegrating by fluid energy in apparatus having multiple crushing or disintegrating zones
• C01B 25/20 - Preparation from elemental phosphorus or phosphoric anhydride
• B02C 21/00 - Disintegrating plant with or without drying of the material
• B02C 23/08 - Separating or sorting of material, associated with crushing or disintegrating
• B02C 23/18 - Adding fluid, other than for crushing or disintegrating by fluid energy
• C01B 25/18 - Phosphoric acid

Abstract

Disclosed is a composite pellet used as a raw material in a kiln process for the production of phosphoric acid, which is of a core-shell structure in which the shell clads the core, wherein the core consists of a core material and a binder, and the shell consists of a cladding material and a binder; the core material mainly consists of a carbonaceous reductant powder, a phosphate ore powder and a silica powder, the cladding material mainly consists of a carbonaceous reductant powder and a silica powder, and the core and the shell are composited by a binder to form the shell-core structure. The preparation of the composite pellets comprises the steps of preparing the cores, preparing the cladding material, shaping, drying and solidifying composite green pellets etc., specifically comprising subjecting the obtained cores to a double-layer roll sieving treatment, then sending same into a pelletiser, introducing the cladding material, adding the binder during the cladding treatment, and obtaining the composite green pellets after the cladding treatment; then sending the composite green pellets to a drier for drying and solidifying, and finally shaping to obtain the composite pellets. The composite pellets prepared by the present invention have a smaller range of formulation fluctuation, more stable quality, higher strength and better performance.

IPC Classes  ?

• C01B 25/01 - Treating phosphate ores or other raw phosphate materials to obtain phosphorus or phosphorus compounds
• C01B 25/18 - Phosphoric acid

Abstract

Disclosed is a comprehensive utilisation method for high-temperature slag balls exiting a rotary kiln in a kiln process for the production of phosphoric acid, comprising a rotary kiln, a cooling device and a drier for composite green pellets in a kiln process for the production of phosphoric acid, wherein the cooling device comprises at least two cooling stages, the hot air outlet of the first cooling stage is connected to the cavity of the rotary kiln via a conveying pipeline, and the hot air outlet of the second cooling stage is connected to the cavity of the drier via a conveying pipeline; the high-temperature slag balls are first conveyed to the cooling device, then the cooling device carries the slag balls successively to multiple cooling stages by the movement of a trolley, each cooling stage introduces cold air for cooling, a part of the hot air after cooling is sent to the cavity of the rotary kiln, and the other part thereof is sent to the drier for composite green pellets in a kiln process for the production of phosphoric acid for drying. A system using the method is also disclosed.

IPC Classes  ?

• C22B 1/02 - Roasting processes
• F27D 17/00 - Arrangements for using waste heatArrangements for using, or disposing of, waste gases
• F27D 15/02 - Cooling
• F27B 7/38 - Arrangements of cooling devices

Abstract

Disclosed is a device for preparing phosphoric acid from a smoke exiting a kiln in a kiln process for the production of phosphoric acid, wherein the device comprises a hydration tower and an acid liquor circulating and spraying system; a phosphoric acid fog capturing tower and a fog removing and separating tower are connected behind the hydration tower; the body of the hydration tower is an empty spraying tower, the lower part of the hydration tower is provided with an inlet for the smoke exiting the kiln, and the top thereof is provided with an outlet for the smoke after hydration absorption; a spraying device is provided in the cavity of the hydration tower above the smoke inlet, the liquid inlet of the acid liquor circulating and spraying system is provided at the bottom of the hydration tower, the liquid outlet of the acid liquor circulating and spraying system is connected to the liquid inlet of the spraying device, and the acid liquor circulating and spraying system is also provided with an acid storage tank and a circulating pump. The present invention has the advantages of simple structure, reasonable layout, low equipment investment cost, strong adaptability, high raw material utilisation rate, reduced contaminant emissions, and high recovery rate of phosphoric acid etc.

IPC Classes  ?

• C01B 25/18 - Phosphoric acid

Abstract

Disclosed is a method for phosphorus absorption by hydration and fluorine recovery for a smoke exiting a kiln in a kiln process for the production of phosphoric acid, comprising the following steps: before a smoke containing P2O5 and fluorine exiting a kiln is first introduced into a hydration tower, an acid liquor circulating and spraying system connected to the hydration tower is turned on, the smoke performs heat and mass transfer with the sprayed liquid, with most of the phosphoric acid produced being absorbed into the sprayed liquid; the phosphoric acid solution falling from the spraying finally enters the acid liquor circulating and spraying system via a liquid inlet; the smoke discharged from a smoke outlet then passes through a phosphoric acid fog capturing tower and a fog removing and separating tower successively, such that the phosphoric acid fog entrained in the smoke exiting the hydration tower is further captured; the concentrated phosphoric acid solution in the acid liquor circulating and spraying system can enter a phosphoric acid refining procedure, and the fluorine-containing smoke discharged from the fog removing and separating tower enters a subsequent fluorine recovery procedure. The present invention has the advantages of simplified process flow, reasonable layout, low equipment investment cost, strong adaptability, meeting environmental standards, and good recovery effects on both phosphorus and fluorine etc.

IPC Classes  ?

• C01B 25/18 - Phosphoric acid
• C01B 33/10 - Compounds containing silicon, fluorine, and other elements

Abstract

Disclosed is an improved method for mass production of phosphoric acid with a rotary kiln, comprising the following steps: pre-treating raw materials of a carbonaceous reductant, a phosphate ore and silica respectively, and then mixing same; preparing the pre-treated carbonaceous reductant powder, phosphate ore powder and silica powder into cores; then evenly mixing the carbonaceous reductant powder and the silica powder to obtain a cladding material; mixing the cores and the cladding material for cladding treatment, drying and solidifying same to obtain composite pellets; sending the composite pellets into a rotary kiln for a reduction reaction; sending the high-temperature slag balls exiting the rotary kiln to a cooling device for comprehensive utilisation; introducing the smoke containing P2O5 and fluorine exiting the kiln into a hydration tower for absorbing phosphorus by hydration, then passing same through a phosphoric acid fog capturing tower and a fog removing and separating tower successively, and the fluorine-containing smoke discharged from the fog removing and separating tower entering a subsequent fluorine recovery procedure. The process flow of the present invention is reasonable and optimized, the equipment investment is low, the economic added value is high, the whole process is energy-saving, environmentally friendly and efficient, and the product quality is excellent.

IPC Classes  ?

• C01B 25/01 - Treating phosphate ores or other raw phosphate materials to obtain phosphorus or phosphorus compounds
• C01B 25/18 - Phosphoric acid
• F27B 7/00 - Rotary-drum furnaces, i.e. horizontal or slightly inclined

Abstract

Disclosed is a device and process for fluorine recovery from smoke after phosphorus absorption by hydration in a kiln process for the production of phosphoric acid, wherein the device comprises a first-stage and second-stage fluorine absorption tower, which are both fluidised counter-current washing towers; the first-stage fluorine absorption tower mainly consists of a fluorosilicic acid washing pipe and a fluorosilicic acid separation tank; the top of the separation tank is provided with a smoke outlet, and at the bottom thereof a fluorosilicic acid liquid outlet is connected to the fluorosilicic acid washing pipe via a circulating and conveying pipeline; the main structure of the second-stage fluorine absorption tower is similar to that of the first-stage fluorine absorption tower, the top of the second-stage fluorosilicic acid separation tank is provided with a defoaming layer and a smoke outlet, and at the bottom thereof a fluorosilicic acid liquid outlet is in communication with a nozzle in the second-stage fluorosilicic acid washing pipe and the fluorosilicic acid separation tank in the first-stage fluorine absorption tower via a circulating and conveying pipeline. The fluorine recovery process of the present invention comprises multiple operations of a first-stage fluorine absorption, a first-stage gas-liquid separation, a second-stage fluorine absorption, and a second-stage gas-liquid separation etc. The present invention has the advantages of simple structure, low investment cost, high raw material utilisation rate, and good fluorine recovery effects etc.

IPC Classes  ?

• C01B 25/18 - Phosphoric acid
• C01B 33/10 - Compounds containing silicon, fluorine, and other elements

Abstract

Disclosed is a rotary kiln for reducing phosphate ore in a kiln process for the production of phosphoric acid, comprising a kiln body, a kiln head box, a kiln tail box and a driving device for driving the rotation of the kiln body, wherein a fuel burner is provided at the kiln head, a feeding pipe and an outlet flue connected to an external hydration tower are provided at the kiln tail box, the upper part of the kiln body is provided with no air pipe, the outlet flue is provided in the radius range of the kiln body with the axis of the rotary kiln as a centre, and the smoke conveying direction in the outlet flue is substantially parallel to the axis direction of the rotary kiln or has an included angle of less than 45° thereto. When using the rotary kiln of the present invention for the kiln process for the production of phosphoric acid, the raw materials enter from the kiln tail box, the fuel burner is ignited for heating, the phosphate ore raw material is reduced under a high-temperature condition to produce a smoke exiting the kiln, and in the present invention, the smoke exiting the kiln is allowed to enter the outlet flue without large shifting, thereby preventing the centrifugal physical sedimentation at the kiln tail such that the metaphosphoric acid in the kiln smoke directly enters the hydration tower along with the kiln smoke. The present invention can effectively mitigate the phenomenon of ring forming in the kiln tail of the rotary kiln.

IPC Classes  ?

• F27B 7/00 - Rotary-drum furnaces, i.e. horizontal or slightly inclined
• C01B 25/18 - Phosphoric acid

Abstract

Disclosed is a raw material pre-treatment process system suitable for a kiln process for the production of phosphoric acid, comprising carbonaceous reductant, phosphate ore and silica pre-treatment systems independent from each other, wherein the outlet of each pre-treatment system is connected to a core material mixing device via a conveying device, the outlets of the carbonaceous reductant and silica pre-treatment systems are connected to a shell material mixing device via an additional conveying device, and each pre-treatment system mainly consists of a single-stage crushing device, an intermediate bin, an ore grinding device, a storage bin and a formulating device. Also disclosed is a raw material pre-treatment process suitable for a kiln process for the production of phosphoric acid, i.e. pre-treating the carbonaceous reductant, phosphate ore and silica with the respective pre-treatment systems, correspondingly, then sending same into the core material mixing device for pelletising, and sending the pre-treated carbonaceous reductant and silica to the shell material mixing device for mixing. The present invention has the significant advantages of reasonable structural optimisation, low cost, small energy consumption and ensuring the stable operation of the kiln process for the production of phosphoric acid etc.

IPC Classes  ?

• C01B 25/18 - Phosphoric acid