阅读说明：本技术 一种湿法炼锌中性浸出过程中pH值的控制方法 (Method for controlling pH value in neutral leaching process of zinc hydrometallurgy ) 是由 朱红求 刘学斌 龙双 阳春华 李勇刚 孙备 于 2019-10-24 设计创作，主要内容包括：本发明涉及一种湿法炼锌中性浸出过程中pH值的控制方法,所述控制方法包括如下步骤：S1、基于物料平衡计算,得到酸与焙砂的比值范围,选取该比值范围为数据样本,采用聚类算法对所述数据样本进行聚类分析得到酸添加量；S2、根据S1步骤中所述的酸添加量得到指定浸出槽出口的pH值；若所述pH值不在预设定的范围内,建立模糊规则得到酸调整量使所述pH值达到预设定的范围。本发明通过数据样本和聚类算法得到酸添加量,算法给定的酸添加量比人工给定值更准确,再通过模糊规则对浸出槽出口pH值进行处理,并调整当前酸添加量得到合适的pH值。(The invention relates to a control method of a pH value in a neutral leaching process of zinc hydrometallurgy, which comprises the following steps: s1, obtaining a ratio range of acid and calcine based on material balance calculation, selecting the ratio range as a data sample, and performing cluster analysis on the data sample by adopting a clustering algorithm to obtain the acid addition amount; s2, obtaining the pH value of the outlet of the designated leaching tank according to the acid addition amount in the step S1; if the pH value is not in the preset range, establishing a fuzzy rule to obtain an acid adjustment amount so that the pH value reaches the preset range. According to the invention, the acid addition is obtained through a data sample and a clustering algorithm, the acid addition given by the algorithm is more accurate than the artificially given value, the pH value of the outlet of the leaching tank is processed through a fuzzy rule, and the current acid addition is adjusted to obtain a proper pH value.)

1. A control method for pH value in neutral leaching process of zinc hydrometallurgy is characterized by comprising the following steps:

s1, obtaining a ratio range of acid and calcine based on material balance calculation, selecting the ratio range as a data sample, and performing cluster analysis on the data sample by adopting a clustering algorithm to obtain the acid addition amount;

s2, obtaining the pH value of the outlet of the designated leaching tank according to the acid addition amount in the step S1; if the pH value is not in the preset range, establishing a fuzzy rule to obtain an acid adjustment amount so that the pH value reaches the preset range.

2. The control method according to claim 1, wherein the preset range is 3 to 3.5.

3. The control method according to claim 1, wherein the ratio of the acid to the calcine is calculated by the formula:

wherein F is the amount of acid and is m³M is the blanking amount of the calcine, the unit is t/h, α is the zinc content of the calcine, β is the leaching rate;

4. The control method according to claim 1, wherein the ratio of the acid to the calcine is in the range of 2.2 to 4.

5. The control method of claim 1, wherein the clustering algorithm comprises a K-Means algorithm.

6. The control method according to claim 1, wherein the step S2 includes:

s21, first input variable pH error e, second input variable pH error change rate e c, output variable for Acid addition △ Acid, the error e expression is:

е＝pH_set-pH_real；

wherein the pH is_setIs an ideal pH value at the outlet of the leaching tank_realIs the actual detected pH value;

s22: dividing the first input variable pH value error e, the second input variable pH value error change rate e and the output variable into a plurality of fuzzy sets respectively;

s23: respectively establishing a first membership function of the first input variable, a second membership function of the second input variable and a third membership function of the output variable;

s24: obtaining a fuzzy result value based on a fuzzy rule of a first input variable pH value error e and a second input variable pH value error change rate e;

s25: and converting the fuzzy result value into a corresponding numerical value by adopting a gravity center method according to the fuzzy result value obtained in the step of S24.

7. The control method of claim 6, wherein the fuzzy set of first input variable pH error e is: { NB, NS, ZO, PS, PB }, where NB denotes negative large, NS denotes negative small, ZO denotes normal, PS denotes positive small, and PB denotes positive large.

8. The control method of claim 6, wherein the fuzzy set of second input variable pH error change rates e, c is: { NB, NS, ZO, PS, PB }, where NB denotes negative large, NS denotes negative small, ZO denotes normal, PS denotes positive small, and PB denotes positive large.

9. The control method according to claim 6, wherein in the step S24, the following fuzzy rule is formulated:

1)IF(е＝ZO and еc＝NB)or(е＝ZO and еc＝ZO)or(е＝ZO and еc＝PS)，THEN△Acid＝ZO；

2)IF(е＝ZO and еc＝NB)or(е＝NS and еc＝ZO)or(е＝NS and еc＝PS)or(е＝NSand еc＝PB)，THEN△Acid＝NS；

3)IF(е＝NS and еc＝NB)or(е＝NS and еc＝NS)or(е＝NB and еc＝PS)or(е＝NBand еc＝PB)，THEN△Acid＝NM；

4)IF(е＝NB and еc＝NB)or(е＝NB and еc＝NS)or(е＝NB and еc＝ZO)，THEN△Acid＝NH；

5)IF(е＝ZO and еc＝PS)or(е＝PS and еc＝NB)or(е＝PS and еc＝NS)，THEN△Acid＝PS；

6)IF(е＝PS and еc＝ZO)or(е＝PS and еc＝PS)or(е＝PS and еc＝PB)or(е＝PBand еc＝NB)or(е＝PB and еc＝NS)，THEN△Acid＝PM；

7)IF(е＝PB and еc＝ZO)or(е＝PB and еc＝PS)or(е＝PB and еc＝PB)，THEN△Acid＝PH；

where NB indicates negative large, NS indicates negative small, ZO indicates normal, PS indicates positive small, PB indicates positive large, NH indicates a large decrease in acid, NM indicates a medium decrease in acid, PM indicates a medium increase in acid, and PH indicates a large increase in acid.

Technical Field

The invention relates to the technical field of smelting, in particular to a method for controlling a pH value in a neutral leaching process of zinc hydrometallurgy.

Background

The neutral leaching process is one of the most important links in the zinc hydrometallurgy process, and aims to dissolve valuable metals in zinc calcine into a solution as much as possible, control the pH value of a neutral leaching terminal to be stabilized within a range of 4.8-5.2, and remove harmful impurity ions such as iron, silicon, arsenic, antimony, germanium and the like by utilizing the hydrolysis coprecipitation effect of partial ions. The neutral leaching process is composed of 6 continuous stirring reaction kettles, and each leaching tank is provided with a calcine blanking bin which continuously adds calcine into the leaching tank through a weighing feeder; adding manganese ore slurry, acid leaching supernatant and mixed liquor into a No. 1 leaching tank, and adding waste acid from an electrolysis process into No. 1, No. 2 and No. 5 leaching tanks respectively. Due to factors such as unstable equipment, large fluctuation of solvent concentration, complex content of mineral source components, large lag time and the like in an actual field, the control quantity is not adjusted timely or accurately, so that the pH is difficult to control in a reasonable range, and the subsequent production process is greatly influenced. Therefore, pH control in industrial processes remains a challenge to be solved.

The pH value control method in the industrial field mainly comprises manual control, wherein the manual control mainly gives a loop set value according to production indexes, assay values and operation conditions by an engineer according to experience. When a fault condition occurs, the set value is changed by experience to gradually recover the system to a normal condition. However, the control method based on experience by the field engineer is easy to cause pH value fluctuation, and cannot reach the preset ideal value.

Disclosure of Invention

Based on this, the control method for the pH value in the neutral leaching process of the zinc hydrometallurgy is provided aiming at the technical problem that the pH value is easy to fluctuate due to the control method based on experience of engineers in the prior art.

A control method for pH value in neutral leaching process of zinc hydrometallurgy comprises the following steps:

s1, obtaining a ratio range of acid and calcine based on material balance calculation, selecting the ratio range as a data sample, and performing cluster analysis on the data sample by adopting a clustering algorithm to obtain the acid addition amount;

s2, obtaining the pH value of the outlet of the designated leaching tank according to the acid addition amount in the step S1; if the pH value is not in the preset range, establishing a fuzzy rule to obtain an acid adjustment amount so that the pH value reaches the preset range.

In some embodiments, the predetermined range is 3 to 3.5.

In some embodiments, the ratio of acid to calcine is calculated by the formula:

wherein F is the acid flow rate and the unit is m³M is the blanking amount of the calcine, the unit is t/h, α is the zinc content of the calcine, β is the leaching rate;M_ZnOrelative molecular masses of sulfuric acid and zinc oxide, respectively;

the acid concentration is selected according to the actual industrial situation.

In some embodiments, the acid to calcine ratio ranges from 2.2 to 4.

In some embodiments, the clustering algorithm comprises a K-Means algorithm.

In some embodiments, the step S2 includes:

s21, first input variable pH error e, second input variable pH error change rate e c, output variable for Acid addition △ Acid, the error e expression is:

е＝pH_set-pH_real；

wherein the pH is_setIdeal pH value for the outlet of a designated leaching tank_realThe pH value actually detected for the outlet of the designated leaching tank;

s22: dividing the first input variable pH value error e, the second input variable pH value error change rate e and the output variable into a plurality of fuzzy sets respectively;

s23: respectively establishing a first membership function of the first input variable, a second membership function of the second input variable and a third membership function of the output variable;

s24: obtaining a fuzzy result value based on a fuzzy rule of a first input variable pH value error e and a second input variable pH value error change rate e;

s25: and converting the fuzzy result value into a corresponding numerical value by adopting a gravity center method according to the fuzzy result value obtained in the step of S24.

In some embodiments, the fuzzy set of first input variable pH error e is: { NB, NS, ZO, PS, PB }, where NB denotes negative large, NS denotes negative small, ZO denotes normal, PS denotes positive small, and PB denotes positive large.

In some embodiments, the fuzzy set of second input variable pH error rates e is: { NB, NS, ZO, PS, PB }, where NB denotes negative large, NS denotes negative small, ZO denotes normal, PS denotes positive small, and PB denotes positive large.

In some embodiments, in step S24, the following fuzzy rule is formulated:

1)IF(е＝ZO and е c＝NB)or(е＝ZO and е c＝ZO)or(е＝ZO and е c＝PS)，THEN△Acid＝ZO；

2)IF(е＝ZO and е c＝NB)or(е＝NS and е c＝ZO)or(е＝NS and е c＝PS)or(е＝NS and е c＝PB)，THEN△Acid＝NS；

3)IF(е＝NS and е c＝NB)or(е＝NS and е c＝NS)or(е＝NB and е c＝PS)or(е＝NB and е c＝PB)，THEN△Acid＝NM；

4)IF(е＝NB and е c＝NB)or(е＝NB and е c＝NS)or(е＝NB and е c＝ZO)，THEN△Acid＝NH；

5)IF(е＝ZO and е c＝PS)or(е＝PS and е c＝NB)or(е＝PS and е c＝NS)，THEN△Acid＝PS；

6)IF(е＝PS and е c＝ZO)or(е＝PS and е c＝PS)or(е＝PS and е c＝PB)or(е＝PB and е c＝NB)or(е＝PB and е c＝NS)，THEN△Acid＝PM；

7)IF(е＝PB and е c＝ZO)or(е＝PB and е c＝PS)or(е＝PB and е c＝PB)，THEN△Acid＝PH；

where NB indicates negative large, NS indicates negative small, ZO indicates normal, PS indicates positive small, PB indicates positive large, NH indicates a large decrease in acid, NM indicates a medium decrease in acid, PM indicates a medium increase in acid, and PH indicates a large increase in acid.

Compared with the prior art, the invention has the following technical effects:

1) the invention overcomes the technical problem that an engineer is easy to cause pH value fluctuation based on an experience-based control method, obtains the acid addition amount by optimizing historical operation information, namely data samples, and a clustering algorithm, the acid addition amount given by the algorithm is more accurate than a manual given value, processes the pH value of the outlet of the leaching tank through a fuzzy rule, and adjusts the current acid addition amount to obtain a proper pH value. The pH value of the outlet of the designated leaching tank can be stabilized within a preset range, and the pH value of the outlet of the tail leaching tank is stabilized at 4.8-5.2.

2) The invention introduces the change trend of the pH value and adjusts in advance through the fuzzy rule, thereby improving the qualification rate of products and reducing the adjusting time.

Drawings

FIG. 1 is a process diagram of a smelting plant hydrometallurgy zinc neutral leaching process;

FIG. 2 is a clustering scatter plot at high acid concentration;

FIG. 3 is a cluster scatter plot at normal acid concentration;

FIG. 4 is a graph of a membership function for pH error;

FIG. 5 is a graph of a membership function of the error rate of pH;

FIG. 6 is a comparative simulation curve of the present invention and a conventional manual control.

Detailed Description

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein, but rather should be construed as broadly as the present invention is capable of modification in various respects, all without departing from the spirit and scope of the present invention.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

A method for controlling the pH value in the neutral leaching process of zinc hydrometallurgy comprises the following steps:

s1, obtaining a ratio range of acid and calcine based on material balance calculation, selecting the ratio range as a data sample, and performing cluster analysis on the data sample by adopting a clustering algorithm to obtain the acid addition amount;

the method comprises the following specific steps: taking a zinc hydrometallurgy neutral leaching process of a certain smelting plant as an example, a process flow chart is shown in fig. 1, the neutral leaching process is composed of 6 continuous stirring reaction kettles, and each leaching tank is provided with a calcine blanking bin for continuously adding calcine into the leaching tank through a weighing feeder; adding manganese ore slurry, acid leaching supernatant and mixed solution into No. 1 leaching tank, and adding acid from electrolysis process into No. 1, No. 2 and No. 5 leaching tanks respectively. The invention aims to ensure that the pH value of the outlet of the tail tank is stabilized within 5 +/-0.2 by automatically adjusting the acid addition amount through a control algorithm.

Firstly, the zinc content α of the calcine is obtained to be 0.52 through statistical analysis of historical data, and the leaching rate β is 0.9;

M_ZnOrelative molecular masses of sulfuric acid and zinc oxide are respectively 98 and 86; the electrolyte concentration was 170 g/l. The material balance calculation is carried out through a chemical reaction equation, and the ratio of acid to calcine is calculated according to the formula:

the ratio of acid to calcine under ideal conditions was found to be 3.14, on the basis of which a data set was selected as a sample, based on a range of acid to calcine ratios from 2.2 to 4, D ═ x₁,x₂,……,x_m}。

And then carrying out cluster analysis on the acid concentration, the acid supernatant flow and the acid-material ratio by adopting a K-Means method, and obtaining the acid concentration which can be divided into three intervals by field investigation and working condition analysis. Respectively as follows: low acid (less than 160g/L), normal (160-180 g/L) and high acid (more than 180 g/L). Dividing the sample set into three sub-sample sets by taking different acid concentrations as a standard, and performing cluster analysis on each sub-sample set, wherein the clustering center k is 3, and the maximum iteration number is 500. And processing the clustering result to obtain the acid-material ratio condition under different acid concentration ranges and acid supernatant flow ranges, and converting the acid-material ratio into the acid addition amount under the current working condition. The K-Means method comprises the following specific processes:

step 1: initializing the clustering algorithm, and setting the maximum iteration number T of the clustering algorithm_MaxAnd the number of the class clusters is k.

Step 2: randomly select k samples from the sample set D as initial centers: { mu. }₁，μ₂，……，μ_k}。

Step 3: computing x in a sample set_j(1<j<m) and Step2_i(1<i<k) According to the distance, the samples close to the initial center are divided into the same cluster C_j. The distance calculation formula is as follows:

d_ji＝||x_j-μ_i||₂

step 4: recalculating new central point position on the basis of dividing the cluster in the way of

Step 5: setting a threshold value if the new center point position mu'_iAnd mu_iIs greater than the threshold value, the current center point position is updated to be mu'_i(ii) a If the central point is smaller than the threshold value, the central point is unchanged.

Step 6: repeating the steps from Step3 to Step5 until the position of the current center point is not updated or the iteration number reaches T_MaxThe algorithm iteration is stopped.

Step 7: and (4) giving a clustering interval of acid concentration, acid supernatant flow and acid-material ratio, and converting into the acid addition amount under the current working condition according to the calcine blanking amount.

The acid addition amount refers to a preset value obtained at the feed forward controller.

Under the condition of high acid concentration, the clustering result is shown in figure 2; under normal acid concentration, the clustering results are shown in fig. 3; under the condition of low acid concentration, the actual site belongs to a special working condition, and concentrated sulfuric acid needs to be increased manually sometimes to reach the normal acid concentration, so that the sample number is insufficient, and the result can be obtained only according to experience. The scatter plot results obtained by clustering were converted into intervals as shown in table 1.

TABLE 1

Acid concentration (g/L)	Acid supernatant flow (m)3/h)	Acid to feed ratio
			>180	<260	2.76
>180	260～310	2.63
			>180	>310	2.47
160～180	<240	3.18
			160～180	240～320	2.93
160～180	>320	2.72
			<160	<280	3.58
<160	280～350	3.26
			<160	>350	2.95

S2, obtaining the pH value of the outlet of the designated leaching tank according to the acid addition amount in the step S1; if the pH value is not in the preset range, establishing a fuzzy rule to obtain an acid adjustment amount so that the pH value reaches the preset range. Wherein the preset range of the pH value is 3-3.5.

The step S2 includes:

s21, first input variable pH error e, second input variable pH error change rate e c, output variable for Acid addition △ Acid, the error e expression is:

е＝pH_set-pH_real；

wherein the pH is_setIs an ideal pH value at the outlet of the leaching tank_realIs the actual detected pH value;

s22: dividing the first input variable pH value error e, the second input variable pH value error change rate e and the output variable into a plurality of fuzzy sets respectively;

according to the production requirement of the neutral leaching process, dividing the pH error e into 5 fuzzy sets: NB (negative large), NS (negative small), ZO (normal), PS (positive small), PB (positive large). ZO indicates that the current pH value is within the process index range, NS indicates that the current pH value is in a slightly lower state, NB indicates that the current pH value is already in an extremely low state, PS indicates that the current pH value is slightly higher, and PB indicates that the current pH value is in a higher state.

The pH error change rate ec is divided into 5 fuzzy sets: NB (negative large), NS (negative small), ZO (normal), PS (positive small), PB (positive large). ZO shows that the pH value is stable in the index range, NS shows that the pH value is in a slow descending trend, NB shows that the pH value is in a rapid descending trend, PS shows that the pH value is in a slow ascending trend, and PB shows that the pH value is in a rapid ascending trend.

The waste Acid addition amount delta Acid is divided into 5 fuzzy sets: NB (large acid reduction), NS (small acid reduction), ZO (constant acid), PS (small acid increase), PB (large acid increase).

S23: respectively establishing a first membership function of the first input variable, a second membership function of the second input variable and a third membership function of the output variable;

the middle three (NS, ZO, PS) fuzzy sets of pH error e and error change rate ec are determined by a bell-type membership function:

wherein the parameters a and b determine the shape of the curve, and the parameter c determines the position of the curve.

The first fuzzy set (NB) of pH error e and error rate of change ec and is determined by type Z membership:

the last fuzzy set (PB) of pH error e and error rate of change ec is determined by the type S membership:

s24: obtaining a fuzzy result value based on a fuzzy rule of a first input variable pH value error e and a second input variable pH value error change rate e;

the middle three fuzzy sets (NS, ZO and PS) of the pH value error e and the error change rate ec are determined by a bell-type membership function, and the first fuzzy set (NB) is determined by a Z-type membership: the last fuzzy set (PB) is determined by the S-type membership. By combining field expert experience and data analysis, the membership function parameters are shown in table 2, and the function distribution is shown in fig. 4 and 5:

TABLE 2

The fuzzy rule of the acid addition amount based on the pH value deviation e and the error change rate ec at the outlet of the 3# leaching tank is shown in Table 3:

TABLE 3

According to the pH value of the outlet of the 3# leaching tank, the acid addition amount is divided into 7 cases: acid (NH) was reduced in large amounts, acid (NM) was reduced moderately, acid (NS) was reduced slightly, acid remained unchanged (ZO), acid (PS) was increased slightly, acid (PM) was increased moderately, acid (PH) was increased greatly.

Rule one is as follows: when the pH value of the 3# leaching tank is in a proper range, the change trend of the pH value is slightly increased or decreased. In this case, it is considered that the amount of the acid added is reasonable and the amount of the acid added is kept constant. The rule is as follows:

IF(е＝ZO and е c＝NB)or(е＝ZO and е c＝ZO)or(е＝ZO and е c＝PS)，THEN△Acid＝ZO；

△ Acid is the amount of Acid added, as follows.

Rule two: when the pH value of the 3# leaching tank is in a proper range, the pH value has a large descending trend, which indicates that the acid is excessive, and the pH value is in a lower or close state to the lower limit of the index in a short time without intervention. When the pH value is lower but the pH value is inclined upward or remains unchanged, the pH value is kept lower. Both of these cases can be classified as a slight excess of acid, and the amount of acid added should be slightly reduced. The rule is as follows:

IF(е＝ZO and е c＝NB)or(е＝NS and е c＝ZO)or(е＝NS and е c＝PS)or(е＝NS and е c＝PB)，THEN△Acid＝NS；

rule three: when the pH value of the 3# leaching tank is in a lower state and the pH value tends to decrease, the condition shows that the pH value is in a lower state in a short time. Or when the pH value is in a very low state but the pH value tends to rise. Both of these cases can be attributed to excess acid, and the acid addition should be moderately reduced. The rule is as follows:

IF(е＝NS and е c＝NB)or(е＝NS and е c＝NS)or(е＝NB and е c＝PS)or(е＝NB and е c＝PB)，THEN△Acid＝NM；

rule four: when the pH value of the 3# leaching tank is in an extremely low state and is in a descending trend or unchanged, the situation shows that the pH value is in an extremely low state in a short time, and the acid is greatly reduced when the acid is added and is excessive. The rule is as follows:

IF(е＝NB and е c＝NB)or(е＝NB and е c＝NS)or(е＝NB and е c＝ZO)，THEN△Acid＝NH；

rule five: when the pH value of the 3# leaching tank is in a proper range, the pH value has a large rising trend, which indicates that the acid is too little, and the pH value is higher or close to the upper limit of the index in a short time without intervention. When the current pH value is in a higher state, but the pH value has a trend of rising, the pH value is indicated to be kept in a higher state or close to an index upper limit state. Both of these cases can be classified as slightly low acid, and the acid addition should be slightly increased. The rule is as follows:

IF(е＝ZO and е c＝PS)or(е＝PS and е c＝NB)or(е＝PS and е c＝NS)，THEN△Acid＝PS；

rule six: when the pH value of the 3# leaching tank is in a higher state, the pH value is kept unchanged or tends to rise, and the situation shows that the pH value is in a higher state in a short time. Or when the pH value is in an extremely high state at present but the pH value tends to decrease. Both of these cases can be classified as acid deficiency and should be moderately increased. The rule is as follows:

IF(е＝PS and е c＝ZO)or(е＝PS and е c＝PS)or(е＝PS and е c＝PB)or(е＝PB and е c＝NB)or(е＝PB and е c＝NS)，THEN△Acid＝PM；

rule seven: when the pH value of the 3# leaching tank is in an extremely high state and the pH value tends to rise or is not changed, the situation shows that the pH value is in an extremely high state in a short time, and the acid addition amount should be greatly increased. The rule is as follows:

IF(е＝PB and е c＝ZO)or(е＝PB and е c＝PS)or(е＝PB and е c＝PB)，THEN△Acid＝PH；

s25: and converting the fuzzy result value into a corresponding numerical value by adopting a gravity center method according to the fuzzy result value obtained in the step of S24, wherein the value is the acid adjustment amount.

The acid adjustment amount is an adjustment amount given based on the case of 3# pH, and the adjustment amount adjusts the amount of acid added in S1.

Due to the reasons that field production equipment has frequent faults, calcine is broken, a flow pneumatic valve is unstable and the like, a control algorithm has certain misjudgment, and the pH value is in a proper range. The evaluation needs to be performed for each given amount of acid. The evaluation criteria are as follows:

considering the total addition amount of the calcine and the total addition amount of the acid in the previous period of time by taking the current time as a reference, the addition amount given by the acid at the current time is obtained to meet the following formula:

wherein m is_ZnOIs the addition amount of the calcine,

adding 1# and 2# acids, rho and mu are upper and lower limits which should be satisfied by the current acid-material ratio, after data analysis, rho is taken to be 2.2, mu is taken4.0。

The acid adjustment amount should satisfy the slow-speed reduction, and under the condition that the calcine discharging amount is not changed, the upward increase of the acid should satisfy the following formula:

wherein a and b are upper and lower limits of acid addition amount when the discharging amount of the calcine is not changed, and a is-40 m³H, b is 20m³/h。

In order to verify the superiority of the method compared with manual control, as shown in fig. 6, the method can correct the acid addition amount in advance according to the change trend of the pH value, so that the pH value of the outlet of the 3# leaching tank is adjusted to be within the production index in time. Particularly, when the discharging amount of the calcined sand is changed in 150min, the acid addition amount given by the control algorithm can track the change of the calcined sand in time and make adjustment in time. Wherein c and m are the acid addition amount given by the control algorithm and the corresponding pH value of the outlet of the 3# leaching tank, and d and n are the artificially controlled acid addition amount and the actual pH value of the outlet of the 3# leaching tank.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.