CN1023862C - Preparation of phosphorus by frunace - Google Patents

Preparation of phosphorus by frunace Download PDF

Info

Publication number
CN1023862C
CN1023862C CN 89100292 CN89100292A CN1023862C CN 1023862 C CN1023862 C CN 1023862C CN 89100292 CN89100292 CN 89100292 CN 89100292 A CN89100292 A CN 89100292A CN 1023862 C CN1023862 C CN 1023862C
Authority
CN
China
Prior art keywords
material piece
phosphorus
section
coke
phosphoric acid
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
Application number
CN 89100292
Other languages
Chinese (zh)
Other versions
CN1044077A (en
Inventor
江善襄
陆友俊
王富生
白锡柱
薛巧民
钟开根
陈忠国
黄尔文
杨淑贞
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
INSTITUTE OF CHEMICAL INDUSTRY MINISTRY OF CHEMICAL INDUSTRY
Design Institute of Sinopec Nanjing Chemical Industry Corp
Original Assignee
INSTITUTE OF CHEMICAL INDUSTRY MINISTRY OF CHEMICAL INDUSTRY
Design Institute of Sinopec Nanjing Chemical Industry Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by INSTITUTE OF CHEMICAL INDUSTRY MINISTRY OF CHEMICAL INDUSTRY, Design Institute of Sinopec Nanjing Chemical Industry Corp filed Critical INSTITUTE OF CHEMICAL INDUSTRY MINISTRY OF CHEMICAL INDUSTRY
Priority to CN 89100292 priority Critical patent/CN1023862C/en
Publication of CN1044077A publication Critical patent/CN1044077A/en
Application granted granted Critical
Publication of CN1023862C publication Critical patent/CN1023862C/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

Links

Images

Classifications

    • CCHEMISTRY; METALLURGY
    • C01INORGANIC CHEMISTRY
    • C01BNON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B25/00Phosphorus; Compounds thereof
    • C01B25/16Oxyacids of phosphorus; Salts thereof
    • C01B25/18Phosphoric acid
    • C01B25/20Preparation from elemental phosphorus or phosphoric anhydride

Landscapes

  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Manufacture And Refinement Of Metals (AREA)

Abstract

The present invention relates to a method for preparing concentrated phosphoric acid from medium grade phosphate ore. Celite and coke are proportionally added into general medium grade phosphate ore, the mixture is milled is crushed into porous material blocks, and the porous material blocks are dried, are dipped into a wrapping agent, are placed in a tunnel kiln, are preheated, and are heated to 1350 DEG C; carbon powder in the material blocks reduces the phosphate ore to obtain element phosphorus steam (P2) and carbon monoxide (CO), the P2 and the CO are oxidated into P2O5 and CO2 in the kiln, and the released heat of oxidization is directly supplied to the required heat of reducing the phosphate ore; kiln gas containing the P2O5 is led into a hydrated tower and is absorbed by recycle acid to obtain phosphoric acid of a high concentration; the reacted material blocks are cooled to be slag blocks which are used for buildings.

Description

Preparation of phosphorus by frunace
The invention belongs to the technical field of directly producing high-concentration phosphoric acid with grade phosphorus mine in general.
The commercial run of producing in the world now phosphoric acid has two kinds: a kind of is to get phosphoric acid with the sulfuric acid decomposing phosphate rock, is called phosphoric acid by wet process; Another kind is with electric furnace rock phosphate in powder to be obtained yellow phosphorus with coke reduction, yellow phosphorus is put into that oxidation obtains phosphorus pentoxide (P in the another set of device again 2O 5), obtain phosphoric acid through aquation, be called electrothermal way phosphoric acid.Can not be directly used in for impure high middle grade phosphorus mine and to produce phosphoric acid by wet process and electrothermal way phosphoric acid need to consume a large amount of electric energy on the one hand, the yellow phosphorus that is got by Electric Cooker on the other hand transfers to and is oxidized to phosphorus pentoxide (P in the another set of device 2O 5) time emits a large amount of heats of oxidation and can't utilize, can only go to cool away with a large amount of cooling waters, and rising steadily of the anxiety of the energy and electricity price limited the development of electrothermal way phosphoric acid.Therefore how to effectively utilize the heat that discharges in the phosphorus oxidation process, make it to be used to reduce the heat of the required consumption of phosphorus ore, promptly in same reactor, carry out the reduction of phosphorus ore and the oxidation of phosphorus simultaneously, again oxidation products is directly sent to aquation and made high-concentration phosphoric acid, become various countries' researcher and thirst for the problem that solves for a long time.
The U.S. according to above-mentioned imagination, utilizes the heat of oxidation of phosphorus to go to supply with the needed heat of reduction phosphorus ore from the '30s in an equipment, and gained contains P 2O 5Gas is sent to hydrated tower and produces phosphoric acid, and the key reaction equipment that adopts is rotary kiln, such as U.S.P.4397826.Main processes with rotary kiln system phosphoric acid is as follows;
(1) ground phosphate rock is added the pellet that ground silica or lime powder and coke powder are mixed and made into 12~16 millimeters of ∮.
(2) entering in the rotary kiln after the pellet drying, is that fuel is fired to 1350~1520 ℃ with pellet with natural gas, and the phosphorus ore in the pellet is restored by coke into element phosphor steam (P 2) from pellet, overflow, meanwhile pass into an amount of air in the kiln phosphorus steam oxidation is become phosphorus pentoxide (P 2O 5), oxidation institute liberated heat directly offers reduction reaction.
(3) will contain P 2O 5Kiln gas is drawn, and imports hydrated tower and obtain high-concentration phosphoric acid with the recycle acid absorption after dedusting.
Realize the subject matter of above-mentioned technology: the one, the coke in the pellet must not be by air in the kiln gas and the oxidation of carbonic acid gas institute before reduction reaction is carried out; The 2nd, the interior each point temperature of strict control kiln to cause widely different rotary kiln " ring formation " to prevent the pellet fusion.
But in existing published technical literature, the premature oxidation of coke and the problem of pellet melting ring formation are not rationally solved all the time in the widely different rotary kiln, therefore do not have so far industrialization with widely different rotary kiln phosphoric acid processed.
The objective of the invention is extensively to compose the middle grade phosphorus mine deposited as raw material take China, the phosphorus that the heat of emitting with phosphorous oxide in a capital equipment goes to reduce in the phosphorus ore also finds suitable purposes as reacted a large amount of waste residues to obtain the low high-concentration phosphoric acid of cost.
The present invention finishes the reduction of phosphorus ore with the tunnel furnace for principal reaction equipment and phosphoric acid is produced in the oxidation of phosphorus.
The reduction of phosphorus ore is to make reductive agent with coke, and the effect that adds silica is to reduce temperature of reaction, and its reaction is as follows:
△H=25508KJ/kgP 2
△H=-26140KJ/kgP 2
△H=-22856KJ/kgP 2
As can be seen from the above equation, react 2. that institute's liberated heat can satisfy reaction needs 1., but reaction is 1. except producing the P of 1 molecule 2Also produce 5 molecule CO outward, if supply air abundance then with CO also all oxidations, the oxidation gross calorific power will be to react 1.92 times of 1. institute's calorific requirement like this, therefore, if air supply does not everywhere add control, tend to cause because local kiln temperature is too high the material melting.The present invention adopts tunnel furnace as principal reaction equipment, in the main reaction section of tunnel furnace a plurality of points for measuring temperature is housed, the add-on of strict control each point air, thus can avoid expecting the fusion of piece.
In order to prevent to expect that coke in the piece is by premature oxidation, the present invention will expect that piece has flooded 1~2 layer of coating agent, coating agent is made by things such as feldspar, saltcake, coke powder, glass cullet and water glass, this coating agent is melted into the liquid rete of heavy-gravity at 900~1150 ℃, and it can stop O in the kiln gas effectively 2, CO 2, H 2O gas prevents the premature oxidation of coke to the invasion of material piece, does not hinder the effusion of phosphorus steam and CO again.
Main processes of the present invention comprises:
1. middle grade phosphorus mine being added silica is mixed in proportion wet-milling with coke and becomes mixed slurry.Silico-calcium molecular proportion (SiO in the compound 2/ CaO) be greater than 2.5, aluminium calcium molecular proportion (Al 2O 5/ CaO) less than 0.06, the amount of allocating into of coke is 1.1 times of the required carbon amount of reduction reaction, compound is worn into the fineness requirement 85% of rear every kind of raw material by 200 orders.
2. mixed slurry dewaters rear moisture 8~12% through dehydration.
3. dehydration back slip is put in the kneader, adds the binding agent of being made up of clay, bentonite, water glass and expects bulk strength to improve, and its amount is 1~3.5% of compound butt.
4. kneaded material is pressed into porous material shape in make-up machine, and its appearance and size will be fit to building industry and use.
5. the coating agent slurries of 1~2 layer silicates are flooded in material piece oven dry back, and the coating agent slurries are to make with feldspar, saltcake, coke powder, glass cullet and water glass, and its ratio is 10~20: 1~5: 0.1~1: 0.5~2: 1~5, and fusing point is lower than 1150 ℃.
6. the material piece of dipping coating agent is laid in after drying and pushes tunnel cave on the dolly, and with the gaseous fuel heating, through preheating, heating up enters the main reaction section, the coke in 1350 ℃ of blanking blocks and phosphorus ore reaction generting element phosphorus steam (P 2) and carbon monoxide (CO), pass into an amount of hot-air to the main reaction section according to each point temperature branch simultaneously, make whole phosphorus steam become phosphorus pentoxide (P with a part of Oxidation of Carbon Monoxide 2O 5) and carbon dioxide (CO 2), be 2~4 hours in the reaction time of main reaction section.
7. containing P 2O 5Kiln gas is drawn hydrated tower from main reaction section and the section that heats up, with recycle acid absorb high-concentration phosphoric acid.Because preheating section, the section that heats up is provided with the flashboard that can mention between main reaction section and the cooling section, so main reaction section and the section that heats up contain P 2O 5Kiln gas can not freely enter in the preheating section and contact with the material piece, avoids P 2O 5Loss.
8. the material piece that reacts after complete enters cooling section, and warp and the cold air countercurrent flow that enters become slag brick after the cooling of material piece, emit from the kiln tail end, for the building use.
The present invention compares the advantage that has with the present disclosed phosphoric acid technology of producing:
1. the present invention and with the contrast of widely different rotary kiln legal system phosphoric acid:
(1) compound of the present invention is to be pressed into the material piece; material piece surface impregnation the coating agent slurries, formed layer protecting film, can prevent effectively that kiln gas from intruding in the material piece the coke oxidation; the coke oxidation ratio is reduced to below 8%, and the reduction ratio of phosphorus reaches more than 85% in the phosphorus ore.
(2) owing to adopt tunnel furnace to finish the reduction of phosphorus ore and the oxidizing reaction of phosphorus, the reduction and the degree of oxidation of each section controlled in the segmentation of tunnel furnace energy, the tolerance of can segmentation controlling temperature and feeding in each section, thereby can keep being in the kiln optimized reaction conditions, improve the reduction ratio of phosphorus ore, and guarantee that the material piece can be by scorification.
(3) owing to the preheating section in tunnel cave, the section that heats up all is equipped with flashboard between main reaction section and the cooling section, make to contain P 2O 5Kiln gas can not freely enter preheating section, has prevented P 2O 5Gas is expected that piece absorbs, and has improved the recovery rate of phosphorus.
(4) because the material piece is in relative static conditions in tunnel furnace, between material piece and the material piece, not friction between material piece and the kiln wall, thus reduced the dust in the kiln gas, improved the quality of phosphoric acid.
(5) because compound is pressed into the porous material piece that is suitable for building use, the reaction rear material piece that finishes burns till and is slag brick, environment is not polluted, and very high strength is arranged, and can directly apply to building industry.
2. the present invention and industrial production phosphoric acid method contrast now:
Wet-process phosphoric acid (WPPA) must be used high-grade phosphorus ore or ore concentrate now, a large amount of sulfuric acid; Though grade phosphorus mine in available with electrothermal way production needs to consume a large amount of electric energy.And middle grade phosphorus mine, silica, coke and coating agent that tunnel furnace method adopts both be the cheap material that extensively existence is easy to obtain, utilized simultaneously the heat of oxidation to go to supply the reduction phosphorus ore required heat, thus energy consumption both saved, and low production cost, phosphoric acid quality height, three-waste pollution is few.
Accompanying drawing 1 is technology block flow diagram of the present invention: phosphorus ore, silica and coke proportion and wear into the fine powder slurry in the wet mill, after dehydration, enter adding additives kneading in the kneader, in make-up machine, be pressed into then porous material piece, flood 1~2 layer of coating agent after the drying, be contained in after drying and enter tunnel cave on the dolly, through preheating, the laggard conversion zone of becoming owner of that heats up, in the main reaction section, finish the reduction of phosphorus ore and the oxidation reaction of phosphorus, product is for containing P 2O 5Kiln gas is introduced into hydrated tower, absorbs with recycle acid, gets finished acid after cooling; The acid mist of discharging from hydrated tower through receive day with fog phosphoric acid, merge in the finished product phosphoric acid.The material piece is complete at the kiln internal reaction, emits from the kiln tail after cooling off, and becomes slag brick and uses for building industry.
Accompanying drawing 2 is tunnel cave schematic diagrames of the present invention, after drying, material piece dipping coating agent is laid on the dolly, approximately opened the sluices into one in car in per 12~20 minutes, shut gate, then the polylith flashboard is mentioned simultaneously, full row dolly advances the stroke of a car, puts down flashboard, and the effect of flashboard is to prevent that main reaction section and intensification from including P 2O 5The kiln gas string is toward preheating section, to improve the recovery rate of phosphorus.1. cold air enters from going out the car end, and by get 700~1000 ℃ of hot-airs 2. with 1350 ℃ of heat material piece countercurrent flows, 2. temperature is just and multiple spot air feed in the kiln everywhere according to main reaction section and the section that heats up for hot-air.Material piece car enters preheating section and is about 1200 ℃ 7. countercurrent flow of flue gas, 8. emptying of kiln gas after the heat exchange, the material piece enters the section that heats up after being preheating to about 1150 ℃, hot-air 2. with coal gas 5. in the section internal combustion that heats up, to expect that piece is rapidly heated 1300~1350 ℃, at this moment reduction reaction is being carried out, element phosphor steam (P 2) and carbon monoxide (CO) overflow the piece from material, meet hot-air 2. and oxidation obtains phosphorus pentoxide (P 2O 5) and carbon dioxide (CO 2), this part contains P 2O 56. kiln gas derives, and the material piece has been warmed up to 1350 ℃, enters the main reaction section by flashboard, and the reduction reaction fierceness is carried out, the P of generation 2And CO, 2. the hot-air that enters with multiple spot carries out oxidation reaction, the heat that discharges is supplied with and is expected that reduction reaction is required in the piece, so constantly carry out, if main reaction section rear portion is gradually few because producing phosphorus, 3. the oxidation heating can fill into coal gas not enough in right amount, as far as possible fully restores to impel the phosphorus ore that last surplus is few.Oxidation produces contains P 2O 54. kiln gas is derived the outer and kiln gas of kiln and is 6. merged towards hydrated tower with preparing phosphoric acid, and the material piece after sufficient reacting is finished enters into 1. countercurrent flow of cooling section and cold air by flashboard, expects that piece becomes slag brick after cold and pulls out outside the kiln from going out car end brake door, uses for building industry.
Example
Add silica and coke mixing with the Yunnan Haikou phosphorus ore, the phosphorus ore composition is P 2O 524.09%, CaO39.94%, SiO 213.78%, Al 2O 51.5%, F2.8%, silica contains SiO 296.74%, coke contains fixed carbon 80.6%.Silico-calcium molecular proportion (SiO in the compound 2/ CaO) be 3.0, aluminium calcium molecular proportion (Al 2O 5/ CaO) be 0.056, carbon phosphorus molecular proportion (C/P 2O 5) be 7.06.The fineness of compound powder is 85% by 200 mesh sieves.Contain P in the compound 2O 5Be 10.26%, adding concentration is 32% waterglass 3%, is pressed into rectangle material piece, two layers of coating agent of dipping after the material piece drying are put into after drying-electric heating pipe type reactor energising heating, pass into nitrogen simultaneously in pipe, carbon dioxide and air, the condition during its compositional modeling tunnel cave operation.The material piece advances to high temperature section from low-temperature zone, when the main reaction section is 1350 ℃, the material piece is 2 hours in the main reaction section time of staying, if the material piece does not flood coating agent, the percent reduction of phosphorus ore is less than 50% after the reaction, and behind two layers of coating agent of material piece dipping, the percent reduction of phosphorus ore can reach more than 88% after the reaction, the oxygenation efficiency of coke is lower than 6%, contains P in the slag brick 2O 5<1.5%.

Claims (3)

1, grade phosphorus mine is produced the method for high-concentration phosphoric acid in a kind of usefulness, and its technological process is:
(1) Rock Phosphate (72Min BPL), silica and coke are mixed in proportion, and wet grinding becomes slip; Mesh-of-grind is 85% by 200 orders;
(2) slip through dewater to water content be 8~12%;
(3) slip after the dehydration is put in the kneader, and adds the binding agent that is made up of clay, bentonite, waterglass, to improve the intensity of material piece;
(4) material through mediating is pressed into porous material piece with make-up machine, and its appearance and size will be fit to building industry and use;
(5) the coating agent slurries of dipping silicates after the material piece drying;
(6) after the material piece of dipping coating agent slurries dries, be laid on the dolly and push tunnel cave, with hot flue gases and gaseous fuel heating, enter the main reaction section through preheating, intensification, under 1350 ℃ of temperature, the coke in the material piece and phosphorus ore reaction generting element phosphorus steam the (P of institute 2) and carbon monoxide (CO), meanwhile pass into an amount of hot-air toward the main reaction section, make whole phosphorus steam become phosphorus pentoxide (P with a part of Oxidation of Carbon Monoxide 2O 5) and carbon dioxide (CO 2);
(7) containing P 2O 5Kiln gas draw from main reaction section and the section that heats up and go forward side by side into hydrated tower, with recycle acid absorb high-concentration phosphoric acid;
(8) the complete material piece of reaction enters cooling section, and with the cold air countercurrent flow that enters this section, cooled material piece becomes slag brick and draws off from the kiln tail end, as building brick;
Material piece dipping silicate coating agent slurries after it is characterized in that drying, these coating agent slurries are made with feldspar, saltcake, coke powder, glass cullet and water glass, and its ratio is 10~20: 1~5: 0.1~1: 0.5~2: 1~5.
2, method according to claim 1 is characterized in that silico-calcium molecular ratio (SiO in the compound 2/ CaO) be 2.5~3.0; Aluminium calcium molecular ratio (Al 2σ 5/ CaO) be 0.06~0.056; The amount of allocating into of coke is 1.1 times of the required carbon amount of reduction reaction.
3, method according to claim 1 is characterized in that adding in the compound binding agent that clay, bentonite, water glass are formed, and its add-on is 1~3.5% of a compound butt.
CN 89100292 1989-01-14 1989-01-14 Preparation of phosphorus by frunace Expired - Fee Related CN1023862C (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN 89100292 CN1023862C (en) 1989-01-14 1989-01-14 Preparation of phosphorus by frunace

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN 89100292 CN1023862C (en) 1989-01-14 1989-01-14 Preparation of phosphorus by frunace

Publications (2)

Publication Number Publication Date
CN1044077A CN1044077A (en) 1990-07-25
CN1023862C true CN1023862C (en) 1994-02-23

Family

ID=4853790

Family Applications (1)

Application Number Title Priority Date Filing Date
CN 89100292 Expired - Fee Related CN1023862C (en) 1989-01-14 1989-01-14 Preparation of phosphorus by frunace

Country Status (1)

Country Link
CN (1) CN1023862C (en)

Families Citing this family (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1040199C (en) * 1993-06-11 1998-10-14 冶金工业部长沙矿冶研究院 Method for producing phosphoric acid by directly reducing phosphate ore
US7910080B2 (en) 2004-06-04 2011-03-22 Jdcphosphate, Inc. Phosphorous pentoxide producing methods
CN100390091C (en) * 2006-04-14 2008-05-28 湖北三新磷酸有限公司 Method for preparing phosphoric acid and byproduct building brick by using phosphatic ore tailings after phosphate ore dressing
WO2008043222A1 (en) * 2006-09-30 2008-04-17 Hubei Sanxin Phosphoric Acid Co. Ltd Method for directly producing phosphoric acid and several silicate or aluminate byproducts from phosphate ore raw materials
CN101118114B (en) * 2007-09-14 2010-09-29 湖北三新磷酸有限公司 Novel industrialization three-way type roll table kiln for directly preparing phosphoric acid with phosphate ore
CN101172588B (en) * 2007-10-16 2010-11-10 四川川恒化工股份有限公司 Method for producing phosphorus pentoxide by phosphorus ore fusion
CN101597039B (en) * 2009-07-08 2011-06-08 湖北兴发化工集团股份有限公司 Method for producing phosphoric acid by utilizing tunnel kiln
CN103288064B (en) * 2013-05-17 2014-10-15 武汉工程大学 Method for producing phosphoric acid from phosphate ore mill tailings
US9783419B2 (en) 2014-09-26 2017-10-10 Jdcphosphate, Inc. Phosphorous pentoxide producing methods and systems with increased agglomerate compression strength
CN109945231A (en) * 2017-12-20 2019-06-28 中国石油天然气集团公司 A kind of spontaneous ignition device and the method using its progress spontaneous ignition
US11858811B2 (en) 2019-06-30 2024-01-02 Novaphos Inc. Phosphorus production methods and systems and methods for producing a reduction product

Also Published As

Publication number Publication date
CN1044077A (en) 1990-07-25

Similar Documents

Publication Publication Date Title
US5766339A (en) Process for producing cement from a flue gas desulfurization process waste product
US3917795A (en) Method of treating coal refuse
US5049198A (en) Calcium sulfate process for the coproduction of Portland cement clinker and concentrated sulfur dioxide adequate to manufacture sulfuric acid
CN100390091C (en) Method for preparing phosphoric acid and byproduct building brick by using phosphatic ore tailings after phosphate ore dressing
US3235330A (en) Recovery of phosphorus values and cement clinker from a phosphatic ore
CN1023862C (en) Preparation of phosphorus by frunace
CN104555946B (en) Method for jointly producing sulphuric acid and cement clinker by using sulphur gas to reduce gypsum
WO2010025620A1 (en) Method and device for producing yellow phosphorus or phosphoric acid by vertical airtight smoke-baffle kiln
CN100484868C (en) Direct phosphorite reducing process for preparing high concentration phosphoric acid and coproducing silicate and aluminate products
CN1040199C (en) Method for producing phosphoric acid by directly reducing phosphate ore
CN101033061A (en) Method of producing phosphoric acid by directly reducing phosphorus ore and co-producing Portland cement grog
CN104211033A (en) Equipment for preparation of phosphoric acid from kiln-discharged flue gas of kiln-method phosphoric acid technology
CN101337684A (en) Method for recovering sulfur and co-producing calcium carbonate from desulphurization gypsum
JPH0516373B2 (en)
US20050002845A1 (en) Method of forming phosphoric acid from phosphate ore
WO2008043222A1 (en) Method for directly producing phosphoric acid and several silicate or aluminate byproducts from phosphate ore raw materials
CN102689882A (en) Method for producing yellow phosphorus by virtue of low grade phosphate rotary hearth furnace method
CN1026403C (en) Method for producing phosphoric acid by special-shaped rotary kiln
CN206069374U (en) A kind of wet bulb bilayer pyrolysis-type phosphoric acid preparation system
Zheng et al. Overview of Current Phosphoric Acid Production Processes and a New Idea of Kiln Method
CN103539091B (en) Method for preparing phosphoric acid by catalytic reduction of low-medium-grade phosphorite
CN206384844U (en) Rotary hearth furnace
US3479138A (en) Process for the recovery of p2o5 from phosphatic ores
CN206069375U (en) A kind of wet lump ore is with addition of char particle type phosphoric acid preparation system
CN106517120A (en) Kiln method for producing phosphoric acid and light aggregate

Legal Events

Date Code Title Description
C06 Publication
PB01 Publication
C10 Entry into substantive examination
SE01 Entry into force of request for substantive examination
C14 Grant of patent or utility model
GR01 Patent grant
C15 Extension of patent right duration from 15 to 20 years for appl. with date before 31.12.1992 and still valid on 11.12.2001 (patent law change 1993)
OR01 Other related matters
C19 Lapse of patent right due to non-payment of the annual fee
CF01 Termination of patent right due to non-payment of annual fee