CN114487025A - Method for controlling content of crystal water in hydrate and application - Google Patents
Method for controlling content of crystal water in hydrate and application Download PDFInfo
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 127
- 239000013078 crystal Substances 0.000 title claims abstract description 97
- 238000000034 method Methods 0.000 title claims abstract description 66
- 229910052602 gypsum Inorganic materials 0.000 claims abstract description 78
- 239000010440 gypsum Substances 0.000 claims abstract description 78
- 238000012544 monitoring process Methods 0.000 claims abstract description 67
- 238000001354 calcination Methods 0.000 claims abstract description 66
- 239000000463 material Substances 0.000 claims abstract description 10
- 238000002425 crystallisation Methods 0.000 claims description 25
- 230000008025 crystallization Effects 0.000 claims description 25
- 230000001276 controlling effect Effects 0.000 claims description 13
- 238000004364 calculation method Methods 0.000 claims description 6
- 150000004683 dihydrates Chemical class 0.000 claims description 6
- 230000001105 regulatory effect Effects 0.000 claims description 4
- 238000005245 sintering Methods 0.000 claims description 3
- 230000000052 comparative effect Effects 0.000 description 7
- 238000012937 correction Methods 0.000 description 6
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 description 3
- 238000010276 construction Methods 0.000 description 3
- 238000001514 detection method Methods 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- ZOMBKNNSYQHRCA-UHFFFAOYSA-J calcium sulfate hemihydrate Chemical compound O.[Ca+2].[Ca+2].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O ZOMBKNNSYQHRCA-UHFFFAOYSA-J 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- 241000084490 Esenbeckia delta Species 0.000 description 1
- 229910052925 anhydrite Inorganic materials 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- PASHVRUKOFIRIK-UHFFFAOYSA-L calcium sulfate dihydrate Chemical compound O.O.[Ca+2].[O-]S([O-])(=O)=O PASHVRUKOFIRIK-UHFFFAOYSA-L 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 108700041286 delta Proteins 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- XLYOFNOQVPJJNP-ZSJDYOACSA-N heavy water Substances [2H]O[2H] XLYOFNOQVPJJNP-ZSJDYOACSA-N 0.000 description 1
- 150000004677 hydrates Chemical class 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000004886 process control Methods 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
- G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
- G01N27/041—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of a solid body
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- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B11/00—Calcium sulfate cements
- C04B11/02—Methods and apparatus for dehydrating gypsum
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B11/00—Calcium sulfate cements
- C04B11/02—Methods and apparatus for dehydrating gypsum
- C04B11/028—Devices therefor characterised by the type of calcining devices used therefor or by the type of hemihydrate obtained
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Abstract
The invention relates to the field of material treatment, in particular to a method for controlling the content of crystal water in a hydrate and application thereof. The method comprises the following steps: using monitoring point N1To NiMonitoring the hydrate to obtain a monitoring signal comprising the instantaneous conductivity R of the hydrate1To RiI is an integer more than or equal to 3, and the monitoring point is arranged on the advancing route of the hydrate; determining a monitoring point N1To NiCorresponding target conductivity R01To R0i(ii) a Calculating a deviation of the instantaneous conductivity from the target conductivity, and adjusting the calcination conditions of the travel route based on the deviation. The method can conveniently and effectively control the content of the crystal water to meet the set requirement, and can realize high uniformity. The inventionThe method of (3) is particularly suitable for use in processes in which gypsum is calcined to remove crystal water.
Description
Technical Field
The invention relates to the field of material treatment, in particular to a method for controlling the content of crystal water in a hydrate and application thereof.
Background
Because the formation temperature regions of some phases in the calcined gypsum are staggered, the gypsum produced under certain conditions is a mixed phase with a certain phase as the main phase, and the mixed phase can comprise dihydrate gypsum, hemihydrate gypsum, soluble anhydrous gypsum and anhydrous gypsum AII. Crystal water is an important guiding parameter for controlling the quality of building gypsum. Theoretically, it is desirable to have as much gypsum dihydrate as possible to form hemihydrate, i.e., as much as possible to approximately 6.2% of the water of crystallization of the building gypsum. The purity of gypsum used in actual production is almost impossible to be 100%, and if used in construction gypsum, the purity is typically 75% to 90%. Thus, to achieve the best quality of the product, it is necessary to more accurately and precisely control the water of crystallization of the building gypsum to be as close as possible to 6.2% x a% (a% being the measured purity of the gypsum used). For example, if the measured purity of gypsum is 85%, the actual theoretical water of crystallization content of the gypsum of construction is 5.27%. That is, to produce building gypsum from gypsum having a purity of 85%, the crystal water should be as high as 5.27% as possible to obtain as much hemihydrate gypsum as possible.
However, in actual production, it is impossible to strictly control the crystal water to the theoretical value of 5.27%. In actual production, the content of crystal water in calcined gypsum fluctuates greatly from batch to batch and from place to place in the same batch.
However, the content and uniformity of crystal water have a great influence on the properties of gypsum, and therefore, a method for conveniently and effectively controlling the content of crystal water is very important.
Disclosure of Invention
The invention aims to overcome the problem that the crystal water content of hydrate (such as gypsum) is difficult to effectively control in the prior art, and provides a method for controlling the crystal water content of the hydrate and application thereof. The method can conveniently and effectively control the content of the crystal water to meet the set requirement, and can realize high uniformity. The method of the invention is particularly suitable for the process of removing the crystal water by calcining the gypsum.
In order to achieve the above object, a first aspect of the present invention provides a method for controlling the crystalline water content in a hydrate, comprising:
using monitoring point N1To NiMonitoring the hydrate to obtain a monitoring signal comprising the instantaneous conductivity R of the hydrate1To RiI is an integer more than or equal to 3, and the monitoring point is arranged on the advancing route of the hydrate;
determining a monitoring point N1To NiCorresponding target conductivity R01To R0i；
Calculating a deviation of the instantaneous conductivity from the target conductivity, and adjusting the calcination conditions of the travel route based on the deviation.
The first two steps do not limit the sequence in actual operation.
In one example, the method further comprises: establishing a functional relation F (x) between the electrical conductivity of the hydrate and the crystal water, and calculating the instant electrical conductivity R according to the F (x)1To RiRespectively corresponding instantaneous water of crystallization C1To Ci。
In one example, the monitoring point N1At the entrance of the travel path for determining the instantaneous conductivity R of the hydrate as it enters the calcination environment1The monitoring signal of (1).
In one example, the monitoring point Ni(i is an optional number)At the maximum) of the hydrate is located at the exit of the travel route for determining the instantaneous electrical conductivity R after the calcination of the hydrateiThe monitoring signal of (1).
In one example, the manner of determining the target conductivity includes: firstly, determining the target conductivity R of the hydrate after calcining and sintering0iThen according to the initial instantaneous conductivity R1And target conductivity R0iDetermining the monitoring point N by gradient calculation2To Ni-1Target conductivity R of02To R0i-1。
In one example, the calculating the deviation of the instantaneous conductivity from the target conductivity further comprises: further calculating the deviation Delta C of the instant crystal water content and the target crystal water contentc(ii) a And based on this Δ CcAdjusting the calcination conditions of the travel route.
In one example, the manner of adjusting the calcination conditions includes: regulating the rotary speed of rotary kiln to V ═ V0+△V，V0Is the current rotary kiln rotation speed, delta V and delta CcAre opposite in sign; delta CcWhen the number is positive, the delta V is negative, namely the rotary speed of the rotary kiln is slowed down; delta CcWhen the number is negative, the delta V is positive, namely the rotary kiln is quickly adjusted.
In one example, the manner of adjusting the calcination conditions further comprises: setting a threshold deviation, wherein the threshold deviation is a determined value less than or equal to delta 10%; when said Δ CcWhen the absolute value of (a) is greater than the threshold deviation, performing the operation of adjusting the calcination condition; when said Δ CcMay not be performed when the absolute value of (d) is not greater than the threshold deviation.
In one example, the material to be treated containing the hydrate includes 50% by weight or more of dihydrate gypsum.
In a second aspect the invention provides the use of a method according to the first aspect of the invention in a gypsum calcination process for controlling the crystal water content of tap gypsum.
The method can monitor and adjust the calcining condition in real time in the calcining process, thereby being capable of adapting to the requirements of various target crystal water contents and efficiently producing the discharged gypsum which accurately meets the requirements and has uniform quality.
The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.
Drawings
FIG. 1 is a F (x) fitting function of example 1 to determine the change in conductivity with respect to the content of water of crystallization.
Detailed Description
The present invention will be described in detail below by way of examples. The described embodiments of the invention are only some, but not all embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The prior art method for controlling the crystal water content is generally to calculate the crystal water removal rate by weighing the outlet gypsum and then adjust the calcination conditions accordingly. The inventor of the present invention finds that the following problems exist in the control mode: 1. hysteresis, the content of crystal water can be known only after the gypsum is calcined, and if the gypsum is found to be unsatisfactory, obvious economic loss is brought; 2. it is difficult to control and regulate accurately, for example, a factory always produces gypsum with a crystal water content of 5%, an ideal calcining condition is determined in empirical search, but if a day suddenly requires gypsum with a crystal water content of 8%, the factory can not find out the appropriate calcining condition quickly, so that the factory can not produce the required gypsum quickly, and the process of searching again brings more economic loss.
Accordingly, the present inventors have studied a method capable of monitoring and adjusting calcination conditions in real time during calcination, thereby ensuring that the resulting product can accurately reach a set crystal water content. The method of the invention can be applied to various hydrates, especially gypsum from various sources, and can quickly and accurately produce products with various required crystal water contents.
The method for controlling the content of the crystal water in the hydrate comprises the following steps:
using monitoring point N1To NiMonitoring the hydrate to obtain a monitoring signal comprising the instantaneous conductivity R of the hydrate1To RiI is an integer more than or equal to 3, and the monitoring point is arranged on the advancing route of the hydrate;
determining a monitoring point N1To NiCorresponding target conductivity R01To R0iI is an integer no less than 3;
calculating a deviation of the instantaneous conductivity from the target conductivity, and adjusting the calcination conditions of the travel route based on the deviation.
The first two steps do not limit the sequence in actual operation.
The invention realizes the real-time monitoring of the removal degree of the crystal water of the hydrate by converting the crystal water into the conductivity, thereby being capable of adjusting the calcining condition in time in the calcining process and controllably and accurately achieving the product with the target crystal water content.
Therefore, preferably, the method further comprises: establishing a change relationship F (x) of the electrical conductivity of the hydrate and the crystal water.
In one example, the method of the present invention further comprises: obtaining the instant conductivity R according to the change rule of F (x)1To RiRespectively corresponding instantaneous water of crystallization C1To Ci。
The variation f (x) may vary from hydrate to hydrate, and therefore the variation f (x) of the conductivity of the hydrate to the water of crystallization is preferably established prior to the method for controlling the water of crystallization. The method for establishing the functional relationship can be, for example, by measuring the electrical conductivity corresponding to different crystal water contents, establishing a scatter diagram containing sufficient data, and then fitting to obtain the functional relationship F (x).
In the present invention, the hydrate crystal water is removed by placing the hydrate on a traveling route filled with a calcination environment, for example, a rotary kiln in a pipeline shape in which the material advances with tumbling stirring.
Sequentially setting monitoring points N on the traveling route1To NiAnd the device is used for monitoring the hydrate to obtain a monitoring signal. i is the total number of monitoring points arranged on the travel route, and i can be an integer greater than or equal to 3, preferably an integer greater than or equal to 5, and more preferably an integer between 5 and 8.
In one example, the monitoring point N1At the entrance of the travel path for determining the instantaneous conductivity R of the hydrate as it enters the calcination environment1The monitoring signal of (1).
In one example, the monitoring point NiAt the outlet of the travelling route, is used for measuring the instantaneous conductivity R after the calcined hydrate is sinterediThe monitoring signal of (1).
The monitoring point N1To NiThe positional relationship between the two members is not particularly limited, and may be uniformly distributed or non-uniformly distributed on the travel route.
The monitoring points divide the traveling route into a plurality of correction sections, and the correction sections are named by the numbers of the monitoring points at the two end points. The correction segment may include a correction segment L determined by adjacent monitoring pointsabA +1 ═ b, e.g. L12、L23……L(i-1)i(ii) a The correction segment can also comprise a correction segment L determined by non-adjacent monitoring pointsacAnd a + n is c, and n is an integer more than or equal to 2.
The method of the invention comprises the following steps: determining a monitoring point N1To NiCorresponding target conductivity R01To R0i。
The determination method includes, for example: firstly, determining the target conductivity T of the hydrate after calcining and sinteringiThen according to the initial instantaneous conductivity R1And target conductivity R0iDetermining the monitoring point N by gradient calculation2To Ni-1Target conductivity R of02To R0i-1。
In one example, the method further comprises: determining each monitoring point N1To NiTarget conductivity R of01To R0iCorresponding target crystal water content D1To DiFor example, it can be obtained by obtaining F (x) as described above.
The gradient calculation method is a calculation method commonly used in mathematics, and the method is briefly described as follows: for the same monitoring point (N)i) Within an arbitrary time period (Δ t)1) Monitoring data (R)i) Making statistics to obtain delta R1＝Ri-R0iDetermining (Δ t) in the time period1)ΔR1Average value of (2)
And so on for the monitoring point (N)i) Within an arbitrary time period (Δ t)j) (j is an integer of not less than 1) monitoring data (R)j) Making statistics to obtain delta Rj＝Rj-R0iDetermining (Δ t) in the time periodj)ΔRjAverage value of (2)
Adjusting the calcining condition according to the gradient calculation result to ensure that
Infinity approaches 0.
The method of the invention comprises the following steps: calculating a deviation of the instantaneous conductivity from the target conductivity, and adjusting the calcination conditions of the travel route based on the deviation.
The calcination conditions include, for example: calcination temperature, traveling speed, stirring speed, or rotary kiln rotational speed (the rotary kiln rotates around the central axis), and the like.
Preferably, the calculating the deviation of the instantaneous conductivity from the target conductivity further comprises: further calculating the deviation between the instant crystal water content and the target crystal water content; and adjusting the calcination conditions of the travel route based on the deviation of the instant water of crystallization from the target water of crystallization content.
In one example, the manner of adjusting the calcination conditions may include: obtain a monitoring point NcImmediate water of crystallization content CcCalculating the deviation Delta C between the target crystal water content of the monitoring point and the target crystal water contentc＝(Dc-Cc)÷DcX is 100%; according to Δ CcAdjusting the calcining temperature and/or the rotary kiln rotation speed; c is an integer between 1 and i.
Regulating the rotary speed of rotary kiln to V ═ V0+△V，V0The current rotary kiln rotation speed is shown, and the delta V is the regulating quantity. Then Δ V and said Δ CcAre opposite in sign; i.e. Delta CcIf the crystal water content is positive, the instant crystal water content is lower than the target crystal water content, and the delta V is negative, namely the rotary speed of the rotary kiln is slowed down; delta CcWhen the crystal water content is negative, the instant crystal water content is higher than the target crystal water content, and the delta V is a positive number, namely the rotary kiln is accelerated.
Preferably, the manner of adjusting the calcination conditions further comprises: setting a threshold deviation which is a certain value less than or equal to delta 10% (e.g. delta 10%, (delta 09%, (delta 18%, (delta 7%, (delta 6%, (delta 5%, (delta 4%, (delta 3%, (delta 2%) and (delta 1%); when said Δ CcWhen the absolute value of (a) is greater than the threshold deviation, performing the operation of adjusting the calcination condition; when said Δ CcMay not be performed, or may be adjusted (i.e., fine-tuned) within the range of the previous adjustment, when the absolute value of (c) is not greater than the threshold deviation.
Preferably, the hydrate to be treated is gypsum. In one example, the gypsum includes dihydrate gypsum (CaSO) containing 2 molecules of crystal water after pretreatment4·2H2O). The content of free water in the gypsum is not particularly limited because the free water contained in the gypsum can be removed quickly under the calcination condition.
The material to be treated may also contain water and various other impurities.
According to one embodiment, the material to be treated contains gypsum. Preferably, the content of dihydrate gypsum in the material to be treated is 50% by weight or more, preferably 80% by weight or more.
In a second aspect the invention provides the use of a method according to the first aspect of the invention in a gypsum calcination process for controlling the crystal water content of de-kilned gypsum.
The method of the first aspect of the invention is particularly suitable for use in a gypsum calcination process. Depending on the application, the gypsum drawn from the kiln is generally required to contain about 0.5 crystal water (i.e., hemihydrate CaSO4·0.5H2O), however, in the prior art, the content of the crystal water cannot be monitored in real time in the calcining process, so that the crystal water removal effect can only be measured after the crystal water is discharged, and the target crystal water content which meets the requirement accurately is difficult to ensure.
The method can monitor and adjust the calcining conditions in real time in the calcining process, thereby being capable of adapting to the requirements of various changed target crystal water contents and efficiently producing the discharged gypsum which accurately meets the requirements and has uniform quality.
The following examples are intended to illustrate specific embodiments of the present invention and should not be construed as limiting the scope of the invention.
The gypsum to be treated selected in the following examples is gypsum subjected to drying pretreatment, and the actual measured purity of the gypsum in the gypsum is 85%.
Example 1
In this example, the aim was to obtain building gypsum, and the target crystal water content after completion of calcination was set to 5.27% when the ideal crystal water content of building gypsum was 5.27%.
(1) Change relationship construction
Taking a small amount of gypsum to be treated, and testing and determining the change relationship F (x) of the conductivity and the crystal water under laboratory conditions, wherein the specific process comprises the following steps: carrying out short-time calcination treatment on the time to be treated, wherein the calcination time is 2-5 minutes each time, and measuring the conductivity and the crystal water data after taking out; this operation was repeated until the water of crystallization was below 0.1. In terms of the crystal water content (unit: weight%) As abscissa, the conductivity (unit: ms/cm) as ordinate, as shown in FIG. 1, using a computer to fit the function equation F (x), F (x) 1.00093+0.92052/(1+ exp (x-x)0)/dx))，R2＝0.9957，x0Is the crystal water content in the gypsum to be treated.
(2) Preparation for calcination
Preparing a long tubular rotary kiln with the length of 34m and the inner diameter of 2.8m, and arranging a first monitoring point N at the inlet of the rotary kiln1Setting the 6 th monitoring point N at the exit6N is set at distances of 10m, 15m, 20m and 25m from the entrance, respectively2、N3、N4And N5. The 6 monitoring points divide the rotary kiln into L in sequence12Segment, L23Segment, L34Segment, L45And L56Section, rotary kiln speed V in L56The crystal water of the section phosphogypsum material is adjusted by taking 5.27 percent as a final index, so that the quality of the discharged material is ensured.
The initial conductivity of the gypsum was measured to be 0.9969ms/cm (i.e., the monitoring point N)1And (3) measuring the instant conductivity data), and substituting the measured instant conductivity data into the function equation F (x) obtained in the step (1) to calculate the content of the crystal water to be 17.8%.
Setting N according to the initial crystal water content and the target crystal water content2Target water of crystallization of 14.1%, N3Target water of crystallization of 11.75%, N4Target water of crystallization of 9.94%, N5Target water of crystallization of 8.14%, N6The target water of crystallization of (5) was 5.27%. Obtaining N according to the function change relationship F (x) of the conductivity of the hydrate and the crystal water2To N6Respectively corresponding target conductivity R2To R60.9087ms/cm, 0.6141ms/cm, 0.3175ms/cm, 0.1612ms/cm and 0.0926ms/cm, respectively.
(3) Calcination process
The gypsum to be treated is fed into the rotary kiln, turned over in the rotary kiln and moved towards the outlet at a speed of 0.3 m/min. The initial calcining temperature is 400 ℃, and the rotary kiln rotating speed is 30 r/min; testing the instant conductivity of each monitoring point and calculating the conductivity deviation, and adjusting the rotating speed when the conductivity deviation exceeds a threshold deviation (set as 3%);
time 1: gypsum reaches N2A monitoring point, measuring the instant conductivity to be 0.9655ms/cm and relative to the target conductivity R2The deviation is 6.25 percent, the rotary kiln speed is adjusted to be 25r/min when the deviation exceeds the threshold deviation;
time 2: gypsum reaches N3A monitoring point for measuring the instantaneous conductivity of 0.6433ms/cm and the target conductivity R3The deviation is 4.76%, when the deviation exceeds the threshold deviation, the rotating speed of the rotary kiln is adjusted to 27 r/min;
time 3: gypsum reaches N4A monitoring point for measuring the instantaneous conductivity of 0.3277ms/cm and the target conductivity R4The deviation is 3.22 percent, the deviation exceeds the threshold deviation, and the rotation speed of the fine tuning rotary kiln is 29 r/min;
time 4: gypsum reaches N5A monitoring point for measuring the instantaneous conductivity of 0.1626ms/cm and the target conductivity R5The deviation of (a) is 0.85%;
the detection shows that the actual average crystal water content of the discharged gypsum is 5.22 percent, the uniformity is 95 percent, and the requirement of high-quality products is met.
The uniformity test mode is as follows: in the same batch of the discharged gypsum product, randomly taking a plurality of (not less than 20) samples in different directions for crystal water determination, and if the crystal water is in the range of target crystal water content +/-3%, determining that the crystal water reaches an expected value, otherwise, determining that the crystal water does not reach the expected value; then, uniformity is the part to the desired value ÷ total parts × 100%.
The actual water of crystallization is the average of the water of crystallization of the above samples.
In addition, 10 furnaces were continuously operated with a target crystal water content of 5.27% in the same manner as in example 1. The actual average crystal water contents of the 10 furnaces were all determined to be within the range of "target crystal water content. + -. 3%", and the uniformity was greater than 92%.
Example 2
The same gypsum was used as in example 1, except that the target water of crystallization content was 8.00%. This example of a process embodying the invention enables gypsum products of any water of crystallization content to be obtained as desired, and thus can be adapted for various applications.
(1) The variation F (x) is the same as in example 1.
(2) The same rotary kiln and monitoring points as in example 1 were used. Setting N according to the initial crystal water content and the target crystal water content2Target water of crystallization of 14.1%, N3Target water of crystallization of 11.65%, N4Target Crystal Water content of 9.94%, N5The target crystal water content of (2) was 8.14%. Obtaining N according to the function change relationship F (x) of the conductivity of the hydrate and the crystal water2To N5Respectively corresponding target conductivity R2To R50.9087, 0.6141, 0.3175 and 0.1612, respectively.
(3) Calcination process
The same amount of gypsum to be treated and moving speed as in example 1 were followed.
Time 1: gypsum reaches N2A monitoring point, measuring the instant conductivity of 0.9793ms/cm and relative to the target conductivity R2The deviation is 7.77 percent, the deviation exceeds the threshold deviation (3 percent), and the rotating speed of the rotary kiln is adjusted to 24 r/min;
time 2: gypsum reaches N3A monitoring point for measuring the instantaneous conductivity of 0.6396ms/cm and the target conductivity R3The deviation is 4.16 percent, the rotary kiln speed is adjusted to 28r/min when the deviation exceeds the threshold deviation;
time 3: gypsum reaches N4A monitoring point for measuring the instantaneous conductivity of 0.3228ms/cm and the target conductivity R3The deviation is 1.67%, the deviation does not exceed the threshold deviation, and the rotation speed of the fine tuning rotary kiln is 29 r/min;
the detection shows that the actual average crystal water content of the discharged gypsum is 8.08 percent, the uniformity is 93 percent, and the requirement of high-quality products is met.
In the same manner as in example 2, 10 furnaces were continuously operated with a target crystal water content of 8.00%. The actual average crystal water contents of the 10 furnaces were all determined to be within the range of "target crystal water content. + -. 3%", and the uniformity was all greater than 91%.
It can be seen that the method of the invention can flexibly adjust the process control at any time according to the set requirement of the target crystal water content, so that the obtained product can more accurately reach the target requirement.
Comparative example 1
The same gypsum was used as in example 1 and the target water of crystallization was also 5.27%.
This comparative example was carried out in a manner conventional in the art by charging gypsum into a rotary kiln and calcining it at empirically derived calcining conditions constant.
This comparative example was conducted using the same rotary kiln as in example 1, in the same amount of gypsum to be treated and moving speed as in example 1.
Except that the calcination conditions were kept constant as the initial conditions of example 1, i.e., the calcination temperature was 400 ℃ and the rotary kiln rotation speed was 30 r/min.
After leaving the rotary kiln at the same time as in example 1, the actual average crystal water content of the gypsum drawn from the kiln was found to be 6.32% and the homogeneity 89%.
It can be seen that the actual crystal water content of the gypsum product obtained by the method has obvious deviation from the target crystal water content, and the uniformity is not good enough.
Comparative example 2
The procedure was carried out in the same manner as in comparative example 1, except that the target content of crystal water was changed to 8.00%.
The calcination conditions were adjusted according to empirical estimation, instead: the calcining temperature is 390 ℃, and the rotary kiln rotating speed is 32 r/min.
The detection shows that the actual average crystal water content of the discharged gypsum is 10.8 percent, and the uniformity is 60 percent.
It can be seen that the method in the prior art is not flexible enough to adjust, can only guess to adjust the calcining condition, has no timely feedback and readjustment in the middle process, can judge whether the product meets the requirements only after the discharged product is obtained, and has high defective rate.
As can be seen from the comparison between the above examples and comparative examples, the method of the present invention can be well adapted to the requirements of various target crystal water contents; the calcining conditions can be monitored and adjusted in real time in the calcining process, so that the product can reach the range within +/-1% of the set crystal water content when being taken out of the kiln; the resulting gypsum product had very good homogeneity. The determination of the calcination conditions by the method (comparative example) in the prior art can be found out by experience mainly, and the calcination conditions can be further adjusted only by judging whether the crystal water content meets the requirements after the gypsum is discharged from the furnace, and the adjusted calcination conditions can not be ensured to obtain a product with higher quality; the deviation of the crystal water content of the kiln gypsum obtained by the method in the prior art from the target content is large, the uniformity is poor, and the performance in practical use is obviously inferior to that of the gypsum obtained by the invention.
The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.
Claims (10)
1. A method for controlling the crystalline water content of a hydrate, comprising:
using monitoring point N1To NiMonitoring the hydrate to obtain a monitoring signal comprising the instantaneous conductivity R of the hydrate1To RiI is an integer more than or equal to 3, and the monitoring point is arranged on the advancing route of the hydrate;
determining a monitoring point N1To NiCorresponding target conductivity R01To R0i；
Calculating a deviation of the instantaneous conductivity from the target conductivity, and adjusting the calcination conditions of the travel route based on the deviation.
2. The method of claim 1, wherein the method further comprises: set up theThe functional relation F (x) of the hydrate conductivity and the crystal water, and calculating the instantaneous conductivity R according to the F (x)1To RiRespectively corresponding instantaneous water of crystallization C1To Ci。
3. Method according to claim 1 or 2, wherein the monitoring point N1At the entrance of the travel path for determining the instantaneous conductivity R of the hydrate as it enters the calcination environment1The monitoring signal of (1).
4. Method according to claim 1 or 2, wherein the monitoring point NiAt the outlet of the travelling route, is used for measuring the instantaneous conductivity R after the calcined hydrate is sinterediThe monitoring signal of (1).
5. The method of claim 1, wherein the determining the target conductivity comprises: firstly, determining the target conductivity R of the hydrate after calcining and sintering0iThen according to the initial instantaneous conductivity R1And target conductivity R0iDetermining the monitoring point N by gradient calculation2To Ni-1Target conductivity R of02To R0i-1。
6. The method of claim 1, wherein said calculating a deviation of the instantaneous conductivity from the target conductivity further comprises: further calculating the deviation Delta C of the instant crystal water content and the target crystal water contentc(ii) a And based on this Δ CcAdjusting the calcination conditions of the travel route.
7. The method of claim 6, wherein the manner of adjusting the calcination conditions comprises: regulating the rotary speed of rotary kiln to V ═ V0+△V，V0Is the current rotary kiln speed, delta V and delta CcAre opposite in sign; delta CcWhen the number is positive, the delta V is negative, namely the rotary speed of the rotary kiln is slowed down; delta CcWhen it is negative, Δ V is positiveNamely, the rotation speed of the rotary kiln is adjusted to be fast.
8. The method of claim 6 or 7, wherein the manner of adjusting the calcination conditions further comprises: setting a threshold deviation, wherein the threshold deviation is a determined value less than or equal to delta 10%; when said Δ CcWhen the absolute value of (a) is greater than the threshold deviation, performing the operation of adjusting the calcination condition; when said Δ CcMay not be performed when the absolute value of (d) is not greater than the threshold deviation.
9. The method according to claim 1, wherein the material to be treated containing the hydrate comprises 50% by weight or more of dihydrate gypsum.
10. Use of a method according to any one of claims 1-9 in controlling the crystal water content of tap gypsum in a gypsum calcination process.
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| CN101549969A (en) * | 2009-04-28 | 2009-10-07 | 浙江大学 | Method of controlling a dihydrate gypsum for preparing alpha-hemihydrate in salt solution |
| CN105057338A (en) * | 2015-07-24 | 2015-11-18 | 北京科技大学 | Method for improving saline alkali soil with steel works sintering flue gas wet desulphurization gypsum |
| US20190330106A1 (en) * | 2016-11-18 | 2019-10-31 | Knauf Gips Kg | Process and apparatus for calcination of gypsum |
| CN113830922A (en) * | 2021-09-26 | 2021-12-24 | 江苏久吾高科技股份有限公司 | Large-particle titanium gypsum, preparation method and application |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101549969A (en) * | 2009-04-28 | 2009-10-07 | 浙江大学 | Method of controlling a dihydrate gypsum for preparing alpha-hemihydrate in salt solution |
| CN105057338A (en) * | 2015-07-24 | 2015-11-18 | 北京科技大学 | Method for improving saline alkali soil with steel works sintering flue gas wet desulphurization gypsum |
| US20190330106A1 (en) * | 2016-11-18 | 2019-10-31 | Knauf Gips Kg | Process and apparatus for calcination of gypsum |
| CN113830922A (en) * | 2021-09-26 | 2021-12-24 | 江苏久吾高科技股份有限公司 | Large-particle titanium gypsum, preparation method and application |
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