Method and system for estimating acid mist concentration

Abstract

The invention relates to a method and system for estimating acid mist concentration in electrolysis plants, on the basis of physical site variables, in order to continuously monitor the pollutant, focused on prediction on the basis of process variables; whereby an acid mist generation model is obtained without relying on chemical measurements.

Description

[0001] METHOD AND SYSTEM FOR PREDICTION, MEASUREMENT, MONITORING AND CONTROL OF ACID MIST

[0002] INTRODUCTION.

[0003] The present invention relates to the mining, electrowinning, and environmental industries. In particular, the present invention relates to a method for estimating / predicting and monitoring and controlling acid mist concentration without requiring chemical measuring equipment (which is slow and requires no laboratory) by using in-situ physical variables to minimize acid mist.

[0004] In the electrowinning processes of copper and other non-ferrous metals, two main half-reactions occur: the reduction of the metal of interest and the oxidation of water (primarily). Reduction half-reaction M +2 M° half-reaction of H2O oxidation 2H + (ac) + O2(g) + 2e- overall reaction

[0005] This implies that, with the production of a metal in the solid state, i.e., the species of interest (M°), there is a parallel increase in the acidity of the electrolyte (H + ) and the emanation of gas molecules, mainly O2(g).

[0006] The gas, like bubbles inside the electrolyte, tends to rise within the liquid (electrolyte) to the liquid-air interface where it bursts; this phenomenon can be modeled, or is associated, with the density of the gas and the liquid, buoyancy forces, surface tension, and others.

[0007] When bubbles burst at the liquid-water interface, small droplets of electrolyte are generated, suspended in the air—an aerosol known as “acid mist.” The literature identifies two types of droplets that form this aerosol: “jet drops” and “film drops.” [Al Shakarji, R. (2012). Mechanisms of acid mist formation in electrowinning (PhD thesis). James Cook University.] It is important to note that the electrolyte is primarily composed of water and sulfuric acid; therefore, this aerosol has negative implications in terms of occupational health (risk of laryngeal cancer), environmental damage, and deterioration of facilities.

[0008] BACKGROUND.

[0009] The legislation in this regard defines a weighted average permissible limit (LPP), related to work environments and indicated at 0.8 mg (milligrams) of sulfuric acid per m 3 (cubic meter) of air in Chile, for Germany it is 0.1 mg of sulfuric acid per m3 and for Peru it is 0.05 mg of sulfuric acid per m 3 For example, in Chilean legislation (DS594), the value must be adjusted for geographical altitude and the duration of the workers' shifts (i.e., exposure time). These permissible limits allow for the definition of a predetermined operating range and a value to be controlled with the method and system proposed in the present invention.

[0010] The measurement of the contaminant (“acid mist”) is performed by installing air suction pump(s) that, at a defined volumetric flow rate (e.g., 2 L / min), allow air to pass from the workplace, for a specific period (generally 4 hours), to a filter that retains the acidic material and releases the gas (oxygen) into the environment. A subsequent chemical analysis of the material in the filter allows the determination of the quantity (mg) of acid present, and the product of the air flow rate and the sampling time allows the calculation of the cubic meters of air in order to define, as a quotient, the measured value of acid mist [in mg of sulfuric acid / m³]. 3 of air]. For example, US OSHA considers the OSHA ID-113 standard: cellulose mixed aster filter, flow rate of 2L / min, and time of 4hrs.

[0011] PROBLEM - DISCRETE MEASUREMENT and / or CHEMISTRY

[0012] Therefore, due to the sampling period of a few hours and the subsequent requirement for chemical analysis of the filter material, which can take days, acid mist measurement is considered to be performed discretely (not continuously). This makes it impossible to continuously monitor the actual level of acid mist in an industrial plant; monitoring that would allow for an in-depth study of the phenomenon to define key variables and, furthermore, to analyze the results of measures adopted at the plant to mitigate this pollutant.

[0013] Notwithstanding the above, attempts have been made (patents) to provide an online (continuous) measurement of acid mist in an industrial plant. For example, patent application no. CL 201502882, registration 56480, entitled: “device for online monitoring of the concentration of acid mist generated in hydrometallurgical processes using sulfuric acid, comprising: mixing means, gas separation means, and a pH measuring sensor; method of operation of said device; and continuous control system of the process environment.”

[0014] Therefore, there is a need for a method and system for estimating the concentration of acid mist in electrolysis plants, based on in-situ physical variables for continuous monitoring of the contaminant, and oriented towards prediction, based on process variables, which can be environmental conditions, and / or control or mitigation, through the modification of these parameters associated with the process variables. With the above, a model for obtaining acid mist is achieved, which is the concentration of at least H2SO4 in air, which can be measured in mg / m³. 3 , without relying on chemical measurements.

[0015] REQUIREMENT - CONTINUOUS MEASUREMENT and PHYSICAL VARIABLE

[0016] The current industry requirement, and problem to be solved, is not necessarily the measurement of the mist as such (mg of sulfuric acid / m³ 3(of air) continuously, basically for two reasons: (1) because the official measurement (legislation) is discrete, and (2) due to the complexities of the internal components for measuring chemical variables. What is required is the measurement of a physical "proxy" variable, which allows for the identification of trends in the behavior of acid mist in a given space and, through appropriate studies and models, the translation of the value of this variable into acid mist values, using the official values ​​measured discretely at the plant as a reference. It should be added that the estimation of a kind of average acid mist emission value must take into account the temporal and spatial distribution of the contaminant within the workplace. A sample taken near a window or well-ventilated area will show a much lower concentration of the contaminant compared to a sample taken in a poorly ventilated area of ​​the plant.A similar situation occurs with measurements taken at different times, due to ambient temperature and wind speed and direction. Understanding the spatiotemporal distribution of the pollutant requires an instrument that measures physical variables and, through modeling, transforms these values ​​into values ​​close to those officially reported.

[0017] DESCRIPTION OF THE FIGURES

[0018] Figure 1 shows an online measuring instrument for PM1,0, PM2,5 and PM10 variables, on cells of the EW electrolysis plant (electrowinning) and in the central corridor.

[0019] Figure 2 shows a general mapping of the electrolysis (EW) plant in two sectors, including in both: (Fig. 2b) side corridors and (Fig. 2a) central corridor. The effect of the decrease in electrolyte temperature on the concentration of particulate matter is noticeable.

[0020] Figure 3a shows an average particle size values, according to the distribution obtained from the three controlled sizes.

[0021] Figure 3b shows a conversion to acid mist values ​​(mg / m3) using, in this case, multiple linear regression. PMx = [3i + 2 * PM1 + [33 * PM2,5 +[34 * PM10; With PMx / PMn concentrations (PM1 ; PM2,s ; PM10)

[0022] Figure 3c shows a concentration of acid mist in the EW building or electrolysis plant.

[0023] Figure 4a shows a comparison with the wind speed in a vicinity of the plant.

[0024] Figure 4b shows a comparison with wind direction in the vicinity of the plant. Figure 4c shows a comparison with ambient temperature in the vicinity of the plant.

[0025] Figure 5 shows a reduction (%) of acid mist in an EW plant after three measures were taken (operating variables, surfactant, and electrolyte temperature).

[0026] Figure 6 shows a log-normal distribution.

[0027] Figure 7 shows the direction and speed of the wind, indicated by arrows, on an EW plant from a neighborhood and how it affects the interior of said plant, in a real test.

[0028] Figure 8 shows a parallel reading of acid mist with pumps (B1, B2) and PMx for different particle sizes.

[0029] Figure 9 shows the comparison between the acid mist concentration measured in horizontal lines and the PM values X , measured by the instrument, to determine the coefficients of the equation.

[0030] Figure 10 shows the estimated / calculated concentration of acid mist over time, determined from the obtained model, with a sampling frequency of 1 data point every 10 minutes. (With an error of less than 1%)

[0031] Figure 11 shows the arrangement of the instruments. Three pumps (B1, B2, B3) were placed for discrete chemical measurement, with the objective of obtaining a triplicate of the actual value, and equipment to detect the concentration of different particle sizes (PMx).

[0032] Figure 12 shows the estimated / calculated concentration of acid mist over time, determined from the obtained model, with a sampling frequency of 1 data point every 1 minute. (With an error of less than 0.5%)

[0033] DESCRIPTION OF THE INVENTION

[0034] The present invention relates to a method for estimating the concentration of acid mist in electrolysis plants, based on in-situ physical variables for continuous monitoring of the contaminant, and oriented towards prediction, based on process variables, which may be environmental conditions, and / or control or mitigation, through the modification of these parameters associated with the process variables. With the above, a model for obtaining acid mist is achieved, which is the concentration of at least H2SO4 in air, which can be measured in mg / m³. 3, without depending on chemical measurements, comprising: a. obtaining, in parallel in an electrolysis plant (EW and Refinery, other electrochemical processes): a.1.- actual measurements of acid mist concentration, to form a database (direct chemical measurement C_real), of said acid mist concentration (expressed in milligrams of acid per cubic meter of air); a.2.- measurements with particulate matter sensors (PM X ) where X refers to a measurement gauge (0.1 - 50), a first plurality of concentrations of different particulate matter fractions; b. establish at least one fitting model, which relates the acid mist concentration as a function, at least, of the concentrations of particulate matter fractions; for example a model of the following type PMx = |3i + Z[3n * PM Xwhere n is the number of predictors between 1 and 20 and x is the sieve size for particle passage between 0.5 and 40. c. capture a second plurality of concentrations of different substantially continuous particulate matter fractions from at least one PMx device, where “x” corresponds to the size equal to or less than the particle size in micrometers (aerosol in this case) at said plant; and d. use the model and said second plurality of concentrations to estimate the acid mist concentration.

[0035] Where establishing at least one multiple linear regression model from step b. is:

[0036] C_real = [3o+ Z[3 X * PM X ; where C_real corresponds to the real (chemical and discrete) measurement and PM Xto the results obtained from the sensor measurements, allowing the coefficients (|3x) of the equation to be obtained. In a preferred configuration, the method also comprises establishing at least one multiple linear regression model from step b. e. Furthermore, in step a.2., from a database or by direct measurement / inspection, along with an estimate of the acid mist concentration (step b), at least one operating process variable (z1), measured or observed directly, and / or meteorological or environmental variable. Where these variables (z1), i ranges from 1 to 40, and z is a continuous, discrete, binary-dichotomous, and / or categorical variable; f. Establishing a relationship between the estimated acid mist concentration (step b) and the z1 variables (step e), allowing the identification of a rate of change (m1) of the acid mist concentration as a function of a change in at least one of the z1 variables: the operating process variables,These may include current density, electrolyte temperature, chemical characterization of the electrolyte which may include surfactant concentration, and by direct measurement, current distribution between electrodes, missing electrodes, % coverage of mechanical barriers generated by anti-fogging spheres, hot spots such as contactors of an electrolytic cell in the building or electrolysis plant, and meteorological or environmental variables such as wind speed and direction outside and / or inside the electrolysis plant, ambient temperature, humidity, ambient ppm, ambient pressure, which are in the vicinity of the plant.

[0037] In another preferred configuration, the method further comprises: in step a and / oc) capturing the particle size measurement from at least one PMX device, using at least two or at least three measuring sieves, to define the particle distribution in the aerosol, wherein in step c) the measurement from at least one PMX device is provided, for each m 2 from the electrolysis plant. In another preferred configuration, the measurement frequency of the previously obtained acid mist parameters data is greater than one day.

[0038] In another preferred configuration, the frequency of obtaining data for the variables (z¡) of operation process, direct measurement or observation and / or meteorological or environmental variables is less than one day, and this data can be compiled into a database.

[0039] In another preferred configuration in step b, the model is:

[0040] PMx = pi + p2* PMi + p3* PM2.5 +[34 * PM10

[0041] In another preferred configuration, the method further comprises: g. mitigating, through the values ​​obtained from f), the concentration of acid mist (H2SO4 mg / m3 of air), through variation / modification of at least one operating process variable; h. repeating steps c. to f. if: h.1 the resulting concentration of acid mist obtained is within a predetermined range, then proceed to step c.; otherwise; h.2. execute step g., to control said acid mist inside the building or in the electrolysis plant.

[0042] In another preferred configuration in stage g) the control is carried out through the management of the superposition of alternating current over direct current, where through the superposition of alternating current over direct current, it allows operation with lower electrolyte temperatures, to mitigate the emission of acid mist, in addition the control of the bubble size is through the management of the superposition of alternating current over direct current, to mitigate the emission of acid mist.

[0043] In another preferred configuration for mitigating acid mist without affecting the electrowinning process, the method further comprises controlling bubble size by manipulating the surfactant concentration within an electrolyte to control bubble coalescence inside the electrolyte. In another preferred configuration in step g), control is achieved by managing the amount of energy, such as fuel and / or electrical energy, supplied to heating equipment to control the electrolyte temperature and mitigate acid mist.

[0044] In another preferred configuration, the method further comprises controlling the temperature of at least one electrolyte by superimposing alternating current onto direct current, where the temperature of the at least one electrolyte is controlled within the range of 10°C to 50°C. This temperature control is achieved by adjusting the superposition of alternating current onto direct current, allowing operation at lower temperatures, for example, from 20°C to 55°C to 10°C to 40°C. This reduces the operating temperature by 10 to 15°C without affecting the electrowinning process of the metal being extracted, and thereby minimizes acid mist.

[0045] In another preferred configuration of the method in stage b, the fitting model is performed by estimating parameters of a statistical distribution, such as: log normal, Weibull, among others, and these parameters are used as predictors in the model.

[0046] The present invention also relates to a system for estimating the concentration of acid mist in electrolysis plants, based on in-situ physical variables for continuous monitoring of the contaminant, and oriented towards prediction, based on process variables, to execute the method described above, which comprises: first means of obtaining measurements, to obtain, in parallel in an electrolysis plant (EW and Refinery, other electrochemical processes): a.1.- actual measurements of acid mist concentration, to form a database (direct chemical measurement C_real), of said acid mist concentration (expressed in milligrams of acid per cubic meter of air); a.2.- measurements with particulate matter (PMx) sensors where X refers to a measurement gauge (0.1 - 50), a first plurality of concentrations of different particulate matter fractions;at least a first processor operatively connected to the first measurement acquisition means configured to establish at least one fitting model relating the acid mist concentration as a function, at least, of the concentrations of particulate matter fractions; second measurement acquisition means configured to capture a second plurality of concentrations of substantially continuous different particulate matter fractions from at least one PMX unit, where “x” corresponds to the particle size equal to or less than the size in micrometers at said plant; and at least a second processor operatively connected to the at least one first processor and the second measurement acquisition means configured to run the fitting model and said second plurality of concentrations to estimate the acid mist concentration. Wherein the first and second processors are the same processor.

[0047] In a preferred configuration, the system further comprises third measurement means operatively connected to at least one first processor and / or at least one second processor, wherein the third measurement means are configured to capture a third plurality of direct measurement concentrations of at least one operating process variable (zi), direct measurement and / or meteorological or environmental variables.

[0048] In another preferred configuration, the system also includes control means for mitigating the concentration of acid mist (H2SO4 mg / m3 of air) by adjusting / modifying at least one operating process variable. The first and / or second processors are configured to analyze the resulting acid mist concentration. If it falls within a predetermined range, it is measured again; otherwise, the control means are modified to mitigate the acid mist within the electrolysis plant. These control means for mitigating the acid mist concentration consist of equipment that manages the superposition of alternating current onto direct current to control electrolyte temperature and / or bubble size, thereby mitigating acid mist emission.

[0049] In another preferred configuration, the control means to mitigate the concentration of acid mist are equipment for handling a surfactant concentration within an electrolyte, to manage coalescence of bubbles inside the electrolyte, and / or the control means to mitigate the concentration of acid mist are equipment for handling the amount of energy (fuel / electrical energy) of heating equipment, to control the temperature of the electrolyte, to mitigate the acid mist.

[0050] The present invention also relates to a computer program product comprising program code that is for performing the method in accordance with the previously cited method when executed on a computer or processor.

[0051] The present invention also relates to a non-transient, computer-readable medium carrying a program code that, when executed by a computer device, causes the computer device to perform the previously cited method.

[0052] Different options described for different technical characteristics may be combined with each other, or with other options known to a person normally versed in the subject, without this limiting the scope of the present application.

[0053] In the context of this request, and without limiting its scope, "at least one" shall be understood to mean one or more of the elements referenced. Therefore, the number of elements referenced does not limit the scope of this request. Furthermore, if more than one element is provided, those elements may or may not be identical, without limiting the scope of this request.

[0054] The grammatical articles "a," "an," "the," and "the," as used herein, are intended to include "at least one," "at least one," "one or more," or "one or more," unless the context indicates or requires otherwise. Therefore, the articles are used herein to refer to one or more of the grammatical objects of the article. By way of example, "a component" means one or more components, and thus more than one component may be contemplated and used in an implementation of the invention. Furthermore, the use of a singular noun includes the plural, and the use of a plural noun includes the singular, unless the context of use requires otherwise.

[0055] The use of terms such as: "includes", "which includes", "including", "has", "which has", "having", "contains", "which contains", "containing", "comprising" or "comprising", even incorporating some grammatical equivalents of these, should generally be understood as open and non-limiting, e.g., not excluding additional unmentioned elements or steps, unless explicitly stated or understood otherwise in the described context.

[0056] In the context of this application, and without limiting its scope, "plurality" shall be understood to mean two or more of the elements referred to herein. Consequently, the number of elements of the plurality referred to does not limit the scope of this application, provided it is greater than or equal to two. Furthermore, these elements of the plurality may or may not be identical to one another without this limiting the scope of this application.

[0057] When the term "approximately" or "around" is used before a quantitative value, these teachings also include the specific quantitative value, unless specifically stated otherwise. As used herein, the term "approximately" or "around" refers to a variation of ±10% of the stated nominal value, unless a range is explicitly stated herein. Unless otherwise stated, if the term "approximately" or "around" is mentioned before the first extreme value of a numerical interval, or a set of numbers, regardless of their mode of representation (e.g., ratios of the type A:B or A / B, where A and B are whole numbers or decimals, among other numerical representations), this term refers to all the numbers stated, and in the case of numerical intervals, to both the first and second extreme values ​​of the interval.For example, a referenced interval of "approximately X to Y" should be read as "approximately X to approximately Y." In various places herein, values ​​are described in groups or ranges. It is specifically intended that the description include each and every member of such groups and ranges individually and in subcombinations, and any combination of the different extreme values ​​of such groups or ranges. For example, an integer in the range of 0 to 40 is specifically intended to describe individually 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, ...

[0058] 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39 and 40, and an integer in the range of 1 to 20 is specifically intended to individually describe 1, 2, 3, 4, 5, 6, 7, 8, 9, 10,

[0059] 11, 12, 13, 14, 15, 16, 17, 18, 19 and 20. The above also applies to decimal numbers with up to two decimal places, that is, up to the hundredth.

[0060] To designate intervals and / or ranges, various expressions can be used, such as "X - Y", "from X to Y", "from X to Y", "from X - Y", "between X and Y", and others used for this purpose.

[0061] Although this application mentions separate modes of implementation, it should be understood that any mode of implementation, and its characteristic features, may be freely combined with any other mode of implementation and its characteristic features, even in the absence of an explicit statement to that effect. It should be understood that the order of the steps or the order in which certain actions are performed is irrelevant as long as these teachings remain operative.

[0062] In addition, two or more steps or actions can be carried out simultaneously.

[0063] The use of any and all examples, or exemplary language in this document, such as "as" or "including," is intended solely to better illustrate the disclosure herein and does not limit the scope of the invention unless expressly stated. Nothing in the specification should be construed as indicating that any unclaimed element is essential to the practice of the disclosure herein. PROPOSED SOLUTION AND APPLICATION EXAMPLES

[0064] The following are examples of applications of this utility model. These examples are provided for illustrative purposes only to provide a better understanding of the invention, but should in no way be considered as limiting the scope of the protection sought. Furthermore, specifications of different technical features described in the examples may be combined with each other, or with other technical features previously described, without limiting the scope of the protection sought.

[0065] Measurement of the physical variable called particle size (PMx), where “x” corresponds to a size equal to or smaller than the particle size in micrometers (aerosol in this case). In general, PM10 can be used. However, based on the aforementioned study, which mentioned droplet ranges between 0.1 and 54 microns, tests have been carried out with PMi.o, PM2.5, and / or PM10 or a mixture thereof. The use of different sizes also allows for defining the particle distribution in the aerosol. Figure 1. Online measurement instrument for PMi.o, PM2.5, and PM10 variables, on EW cells and in the central aisle of one in an electrolysis plant.

[0066] Next, online monitoring (continuous over time, at intervals of less than 1 minute) was conducted in both fixed and variable positions. This is shown in Figure 2, which presents a general mapping of the electrolysis (EW) plant in two sectors, including: (Fig. 2b) side aisles and (Fig. 2a) the central aisle. The effect of the decrease in electrolyte temperature on the concentration of particulate matter is evident.

[0067] A comparison is then made of the PMx trend over time with the official acid fog values ​​reported by the plant. The fitting model uses meteorological variables (ambient temperature, wind speed and direction), and process and operational variables, as shown in the dashboard of Figures 3a, 3b, and 3c. These figures show the conversion to acid fog values ​​(mg / m³) using multiple linear regression; specifically, Figure 3c shows the final model results in mg / m³. 3 The next step may be the removal of the outer layer or other data from meteorological variables, which are observed in figures 4a, 4b and 4c, where the oscillation of particle size (in blue) with respect to: wind speed and direction, and ambient temperature.

[0068] The next step may be the use of the model to evaluate results in acid mist mitigation, as seen in Figure 5 which shows a reduction (%) of acid mist in EW plant after three measures adopted (operating variables, surfactant, and electrolyte temperature) in 2024.

[0069] • The contaminant is distributed in an unknown way within the electrolysis plant.

[0070] • A sample is taken with a laboratory, with results every 4 hours.

[0071] • With the same emissions of pollutants, the concentration of fog varies due to meteorological variables.

[0072] • Pre-select the measurement points, associated with the measurement of an external certification entity.

[0073] • GPS to safely and accurately determine location, with an accuracy of less than 15 meters.

[0074] • It is set to (“setting”) or default value 4 or 5 particle size and the reading is started for at least 1 day of measurement.

[0075] A plurality of data (Average, min, max, mode) of particle size (aerosol), micro / nano droplets of electrolyte, H2SO4, H2O, + SALT (Copper sulfate, Zinc sulfate or nickel or cobalt, non-ferrous metallic species, species of interest to be analyzed).

[0076] A Log normal distribution is shown for reference, as shown in Figure 6. Input data: Current, Electrolyte temperature, surfactant addition and concentration, pH, % coverage of mechanical bars.

[0077] The focus is on preventing the free oxygen bubbles from bursting (or minimizing) the aerosol released into the EW plant environment. 68-micron bubbles allow the bubbles to recover. 0.1 to 50-micron jet drops can be achieved using nanobubbles with DC-AC, thus preventing acid mist. This has been combined with surfactant to increase surface tension and / or mechanical barriers, such as plastic spheres.

[0078] Climate variables outside the electrolysis plant, among the most important are the direction and speed of the wind.

[0079] The sensor is moved every time (4-5 min) to a distance of 5 m, or multiple sensors can be obtained.

[0080] With all variables of the electrolysis plant constant, the measurement varies during the day, due to the wind that exists outside the electrolysis plant.

[0081] Maintain the electrolysis plant free of external contaminants and at a constant temperature to avoid energy loss due to convection. Ventilation is kept low when there are few windows in the EW electrolysis plant.

[0082] Furthermore, by using alternating current (AC) signals superimposed on the direct current (DC) level, it is possible to operate the cells with electrolyte at a lower temperature and therefore with less emission of acid mist into the environment of the electrolysis plant.

[0083] Another example of the expansion of the present method and system is shown in Figures 8 to 10, where the parallel measurement of acid mist with pumps (B1, B2) and PM X For different particle sizes, the instrument allows determining the coefficients of the equation. Parallel measurement - AMC measured (b1 and b2, in duplicate) and PMx (unit) where x = 1.0, 2.5, 4.0, and 10.0

[0084] The model used was:

[0085] The coefficients obtained were:

[0086] The model obtained with this example was “more parsimonious” than other alternatives (which used a greater number of predictors - particle sizes).

[0087] AMC: (Acid mist concentration) acid mist concentration.

[0088] Subsequently, the resulting model, fed with PMx data, is used to estimate the concentration of acid mist and thus observe how each of the process variables influences this pollutant. For example, at the end of Figure 10, the effect of reducing the electrically applied current intensity to practically zero is shown, which lowers the mist concentration inside the plant. The resulting model achieves an error of less than 1%.

[0089] Another example of the expansion of the present method and system is shown in Figures 11 and 12, where the parallel measurement of acid mist with pumps (B1, B2, B3) for discrete chemical measurement, with the objective of having a triplicate of the real value, and PMx for different particle sizes of the instrument allows the determination of the coefficients of the equation.

[0090] Parallel measurement - ACM measured (B1, B2, B3, in triplicate) and PMx (unit) where x = 1.0, 2.5, 4.0, and 10.0

[0091] The model used was:

[0092] AMC measured = 30+ 3- - PM 1 0 + p2■ PM 2 5 + ?3■ PM 4 o + p4■ PM 10 0

[0093] The coefficients obtained were:

[0094] As shown in Figure 12, the estimated / calculated concentration of acid mist over time, determined from the obtained model, with a sampling frequency of 1 data point every 1 minute. (With an error of less than 0.5%).

Claims

CLAIMS 1. A method for estimating the concentration of acid mist in electrolysis plants, based on in-situ physical variables for continuous monitoring of the contaminant, and oriented towards prediction, based on process variables, CHARACTERIZED in that it comprises: a. obtaining, in parallel in an electrolysis plant: a.

1. actual measurements of acid mist concentration, to form a database (direct chemical measurement C_real), of said acid mist concentration; a.

2. measurements with particulate matter (PMx) sensors where X refers to a measurement range (0.1 - 50), a first plurality of concentrations of different particulate matter fractions; b. establishing at least one fitting model, which relates the acid mist concentration as a function, at least, of the concentrations of particulate matter fractions; c.capture a second plurality of concentrations of different substantially continuous particulate matter fractions from at least one PMx instrument, where “x” corresponds to the size equal to or less than the particle size in micrometers at said plant; and d. use the model and said second plurality of concentrations to estimate the concentration of acid mist.

2. The estimation method of claim 1, CHARACTERIZED in that establishing at least one multiple linear regression model of step b. is: C_real = [3o+ Z[3x* PM X ; where C_real corresponds to the actual measurement and PMx to the results obtained from the measurement with sensors, which allows obtaining the coefficients ((3 X ) of the equation.

3. The estimation method of claim 1 or 2, CHARACTERIZED in that it further comprises establishing at least one multiple linear regression model of step b. is: e. further obtaining in step a.2., from a database or by direct measurement / inspection, at least one operating process variable (z¡), from direct measurement or observation and / or meteorological or environmental variables; f. establishing a relationship between the estimated acid mist concentration (step b) with the variables Z¡ (step e), which allows identifying a rate of change (mi) of the acid mist concentration as a function of a change in at least one of the variables Z¡.

4. The estimation method of claim 1 or 2, CHARACTERIZED in that it comprises: in step a and / oc) capturing the particle size measurement of at least one PMx device, using at least two or at least three measuring sieves, to define the particle distribution in the aerosol.

5. The estimation method of claim 1 or 2, CHARACTERIZED in that it comprises: in step c) the measurement of at least one PMx device is provided, for each m 2 of electrolysis plant.

6. The estimation method of claim 1, CHARACTERIZED in that the measurement frequency of the data, of the previously obtained acid mist parameters, is greater than one day. 7.- The estimation method of claim 3, CHARACTERIZED in that the frequency of obtaining the data of the variables (z¡) of operation process, measurement or direct observation and / or meteorological or environmental variables are less than one day.

8. The estimation method of claim 1 or 2, CHARACTERIZED in that in step b. the model is: PMx = pi + p2* PMi + p3* PM2.5 + p4* PM10 9. The estimation method of claim 1 or 7, CHARACTERIZED in that, for control purposes, the method further comprises: g. mitigating, through the values ​​obtained from f), the concentration of acid mist (H2SO4mg / m³). 3 (of air), through variation / modification of at least one operating process variable; h. repeat steps c. to f. if: h.1 the result of the acid mist concentration obtained is within a predetermined range, then proceed to step c.; if not; h.

2. execute step g., to control said acid mist inside the electrolysis plant.

10. The estimation method of claim 9, CHARACTERIZED in that it comprises: In stage g) control is achieved through the manipulation of the superposition of alternating current over direct current.

11. The estimation method of claim 10, CHARACTERIZED in that, through the superposition of alternating current over direct current, it allows operation with lower electrolyte temperatures, to mitigate the emission of acid mist.

12. The estimation method of claim 10, CHARACTERIZED in that the bubble size control is through the manipulation of the superposition of alternating current over direct current, to mitigate the emission of acid mist.

13. The estimation method of claim 9, CHARACTERIZED in that, to mitigate the acid mist without affecting the electrowinning process, it comprises controlling a bubble size through the manipulation of a surfactant concentration within an electrolyte, to manage coalescence of the bubbles within the electrolyte.

14. The estimation method of claim 9, CHARACTERIZED in that it comprises: In stage g) control is carried out through the management of the amount of energy of heating equipment, to control the temperature of the electrolyte, to mitigate the acid mist.

15. The estimation method of claim 10, CHARACTERIZED in that it comprises controlling the temperature of at least one electrolyte through the superposition of alternating current over direct current.

16. The estimation method of claim 15, CHARACTERIZED in that the temperature control of at least one electrolyte is in the range of 10°C and 50°C. 17.- The estimation method of claim 1, CHARACTERIZED in that in step b. the fitting model is performed by estimating parameters of a statistical distribution, such as: log normal, Weibull, among others and said parameters are used as predictors in the model.

18. A system for estimating the concentration of acid mist in electrolysis plants, based on in-situ physical variables for continuous monitoring of the contaminant, and oriented towards prediction, based on process variables, to execute the method of one of claims 1 to 17, CHARACTERIZED in that it comprises: first means for obtaining measurements, to obtain, in parallel in an electrolysis plant: a.1.- actual measurements of acid mist concentration, to form a database (direct chemical measurement C_real), of said acid mist concentration; a.2.- measurements with particulate matter (PMx) sensors where X refers to a measuring gauge (0.1 - 50), a first plurality of concentrations of different particulate matter fractions; at least a first processor operatively connected to the first means of obtaining measurements configured to establish at least one fitting model, relating the acid mist concentration as a function, at least, of the concentrations of particulate matter fractions; a second measurement acquisition means configured to capture a second plurality of concentrations of different substantially continuous particulate matter fractions from at least one PMx device, where “x” corresponds to the size equal to or less than the particle size in micrometers at said plant; and at least a second processor operatively connected to the at least one first processor and the second measurement acquisition means configured to run the fitting model and said second plurality of concentrations, to estimate the acid mist concentration.

19. The estimation system of claim 18, CHARACTERIZED in that it further comprises third measurement-obtaining means operatively connected to at least one first processor and / or to at least one second processor, wherein the third measurement-obtaining means are configured to capture a third plurality of direct measurement concentrations of at least one operating process variable (zi), direct measurement and / or meteorological or environmental variables.

20. The estimation system of claim 18 or 19, CHARACTERIZED in that it further comprises control means for mitigating the concentration of acid mist (H2SO4 mg / m3 of air), through modification of at least one operating process variable; wherein the at least one first processor and / or the at least one second processor is configured to analyze the result of the acid mist concentration obtained; if it is within a predetermined range, it is measured again; if not, the control means are modified to mitigate said acid mist within the electrolysis plant.

21. The estimation system of claim 20, CHARACTERIZED in that the control means for mitigating the concentration of acid mist are equipment for handling the superposition of alternating current over direct current, to control the electrolyte temperatures and / or bubble size, to mitigate the emission of acid mist.

22. The estimation system of claim 20, CHARACTERIZED in that the control means for mitigating the concentration of acid mist are equipment of managing a surfactant concentration within an electrolyte, to manage bubble coalescence inside the electrolyte.

23. The estimation system of claim 20, CHARACTERIZED in that the control means for mitigating the concentration of acid mist are energy handling equipment of heating equipment, to control the temperature of the electrolyte, to mitigate the acid mist.

24. A computer program product comprising program code CHARACTERIZED in that it is for performing the method according to any one of claims 1 to 17 when executed on a computer or processor.

25. A non-transient, computer-readable medium carrying program code CHARACTERIZED in that, when executed by a computer device, it causes the computer device to perform the method of any one of claims 1 to 17.

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