Dehydration accelerator

Abstract

To provide a dehydration accelerator that is highly effective in dehydration and also has low foaming and foam stability.SOLUTION: A dehydration accelerator for ore slurry containing an ethylene oxide / propylene oxide copolymer represented by the following general formula (1), in which the number average molecular weight of the copolymer is from 900 to 10000, the total weight percentage of ethylene oxide groups based on the total weight of the copolymer is from 21 wt.% to 85 wt.%, and the content of the copolymer is from 50 wt.% to 100 wt.% of the total weight of the dehydration accelerator. R1O-(AO)n-H (1) In the formula (1), R1 represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms and (AO)n represents a poly(alkyleneoxy) group comprising 11 or more ethyleneoxy groups and 1 or more propyleneoxy groups.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a dehydration accelerator used for dehydrating ore slurries.

Background Art

[0002] In a method of transporting particles of ores such as iron and copper or ceramics, there is a means of mixing the particles with water and transporting them as a slurry (also referred to as slurry transportation). It is necessary to dehydrate the slurry-transported particles before transporting them by ship or the like. Adding a dehydration accelerator has been reported as one means of improving the dehydration efficiency of the slurry. As dehydration accelerators, low molecular weight block copolymers of ethylene oxide and butylene oxide described in Patent Document 1 and alkoxylated alkanols described in Patent Document 2 are known. However, these dehydration accelerators have problems in that the dehydration effect is insufficient and the foaming property and foam stability are high, making the dehydration treatment difficult.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present invention has been made in view of the problems of the above prior art, and an object of the present invention is to provide a dehydration accelerator for ore slurries that has a high dehydration effect and further has low foaming property and foam stability.

Means for Solving the Problems

[0005] As a result of intensive studies to solve the above problems, the present inventors have reached the present invention. That is, the present invention is a dehydration accelerator for ore slurries containing an ethylene oxide / propylene oxide copolymer represented by the following general formula (1), wherein the number average molecular weight of the copolymer is 900 to 10,000, and based on the total weight of the copolymer, the total weight ratio of ethyleneoxy groups is 21% by weight to 85% by weight, and the content of the copolymer is 50 to 100% by weight based on the total weight of the dehydration accelerator.

[0006] R 1 O-(AO)n-H (1) "In formula (1), R 1 represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, (AO)n represents a poly(alkyleneoxy) group composed of 11 or more ethyleneoxy groups and 1 or more propyleneoxy groups, and the bonding order of the ethyleneoxy groups and propyleneoxy groups constituting the poly(alkyleneoxy) group may be random or block."

Advantages of the Invention

[0007] The dehydration accelerator for ore slurries of the present invention can provide a dehydration accelerator having a high dehydration effect and further low foaming property and foam stability.

Embodiments for Carrying Out the Invention

[0008] <Copolymer> The dehydration accelerator for ore slurries of the present invention contains an ethylene oxide / propylene oxide copolymer represented by the following general formula (1). In the following, the dehydration accelerator for ore slurries is also simply referred to as a dehydration accelerator. R 1 O-(AO)n-H (1)

[0009] In formula (1), R 1 represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. R 1 When R has an alkyl group having 5 or more carbon atoms, the dehydration property decreases. Examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, an isobutyl group, and a tert-butyl group. R 1 From the viewpoint of dehydration property, a hydrogen atom and an alkyl group having 3 or less carbon atoms (methyl group, ethyl group, n-propyl group, and isopropyl group) are preferable, and a hydrogen atom is most preferable.

[0010] In formula (1), (AO)n represents a poly(alkyleneoxy) group composed of 11 or more ethyleneoxy groups and 1 or more propyleneoxy groups. When the number of ethyleneoxy groups contained in the poly(alkyleneoxy) group is 10 or less, the hydrophilicity of the ethylene oxide / propylene oxide copolymer (hereinafter sometimes referred to as copolymer) becomes insufficient, the solubility of the copolymer in the ore slurry deteriorates, and the dehydration property deteriorates. Further, when the number of propyleneoxy groups contained in the poly(alkyleneoxy) group is 0, the dehydration property becomes insufficient. From the viewpoints of foaming property and foam stability, the number of ethyleneoxy groups contained in the poly(alkyleneoxy) group represented by (AO)n is preferably 11 or more and 220 or less, and the number of propyleneoxy groups contained in the poly(alkyleneoxy) group is preferably 8 or more and 45 or less.

[0011] The ratio [x / y] of the number of moles (x) of the ethyleneoxy group to the number of moles (y) of the propyleneoxy group is preferably 0.4 / 1 to 3 / 1 from the viewpoints of hydrophilicity and dehydration property.

[0012] The bonding order of 11 or more ethyleneoxy groups and 1 or more propyleneoxy groups constituting the poly(alkyleneoxy) group is not particularly limited and may be random or block. A poly(alkyleneoxy) group in which ethyleneoxy groups and propyleneoxy groups are randomly bonded can be obtained by subjecting ethylene oxide and propylene oxide to a ring-opening addition reaction simultaneously (randomly) in the method for producing a copolymer described below. A poly(alkyleneoxy) group in which the bonding order of ethyleneoxy groups and propyleneoxy groups is block can be obtained by subjecting ethylene oxide and propylene oxide to ring-opening addition reactions in sequence in the method for producing a copolymer described below.

[0013] As the poly(alkyleneoxy) group, a poly(alkyleneoxy) group composed of 11 or more ethyleneoxy groups and 2 or more propyleneoxy groups is preferable. From the viewpoint of foam stability, a poly(alkyleneoxy) group in which a first poly(ethyleneoxy) group, a poly(propyleneoxy) group, and a second poly(ethyleneoxy) group are bonded in sequence, and the total number of moles of ethyleneoxy groups contained in the first poly(ethyleneoxy) group and the second poly(ethyleneoxy) group is 11 or more is preferable.

[0014] R in the general formula (1) 1 The type of, and the number and bonding order of ethyleneoxy groups and propyleneoxy groups constituting the poly(alkyleneoxy) group represented by (AO)n can be specified by 1 analyzing by H-NMR (nuclear magnetic resonance spectroscopy).

[0015] The number average molecular weight of the ethylene oxide / propylene oxide copolymer represented by the general formula (1) is 900 to 10000, preferably 1000 to 8000, more preferably 1100 to 6500, and particularly preferably 1200 to 5000. If it is less than 900, the dehydration effect is insufficient, and if it is greater than 10000, the viscosity of the aqueous solution of the dehydration accelerator becomes high and it is difficult to add it to the ore slurry.

[0016] The number average molecular weight (Mn) in the present invention can be measured by gel permeation chromatography (GPC) under the following conditions. Apparatus: "HLC-8320GPC" [manufactured by Tosoh Corporation] Columns: "TSKgel Guardcolumn SuperH-L" (1 piece), "TSKgel SuperH4000", "TSKgel SuperH3000", "TSKgel SuperH2000" (3 pieces) [all manufactured by Tosoh Corporation] Sample solution: 0.25 wt% tetrahydrofuran solution Solution injection volume: 10 μl Flow rate: 0.6 ml / min Measurement temperature: 40 °C Detector: Refractive index detector Standard substance: Standard polystyrene

[0017] The total weight of ethyleneoxy groups contained in the ethylene oxide / propylene oxide copolymer represented by the general formula (1) is 21 wt% to 85 wt%, preferably 21 wt% to 50 wt%, based on the total weight of the ethylene oxide / propylene oxide copolymer. If the total weight ratio of ethyleneoxy groups is less than 21 wt%, sufficient dehydration performance is not achieved, and if it is greater than 85 wt%, the foaming property becomes high and the dehydration treatment becomes difficult.

[0018] It is preferable that the cloud point of the ethylene oxide / propylene oxide copolymer represented by the general formula (1) is 30 to 80 because the copolymer can be recovered from the water dehydrated and removed from the ore slurry.

[0019] The cloud point of the ethylene oxide / propylene oxide copolymer is the value measured by a MeltingPoint System MP80 manufactured by Mettler Toledo using a 1 mass% aqueous solution of the ethylene oxide / propylene oxide copolymer.

[0020] The ethylene oxide / propylene oxide copolymer represented by the general formula (1) is obtained by subjecting ethylene oxide and propylene oxide to ring-opening addition to a compound having an active hydrogen by a known method. R1 When R is a hydrogen atom, it can be obtained by a method of subjecting ethylene glycol or propylene glycol to ring-opening addition of ethylene oxide and propylene oxide in an order according to the bonding order, and a method of subjecting ethylene glycol or propylene glycol to ring-opening addition of a mixture of ethylene oxide and propylene oxide, etc. R 1 When R is an alkyl group having 1 to 4 carbon atoms, it can be obtained by a method of subjecting an alcohol having 1 to 4 carbon atoms to ring-opening addition of ethylene oxide and propylene oxide in an order according to the bonding order, and a method of subjecting an alcohol having 1 to 4 carbon atoms to ring-opening addition of a mixture of ethylene oxide and propylene oxide, etc.

[0021] As the ethylene oxide / propylene oxide copolymer represented by the general formula (1) contained in the dehydration accelerator for ore slurry of the present invention, the copolymers represented by the following general formulas (2) and (3) are preferable from the viewpoint of foam stability. Here, EO represents an ethyleneoxy group and PO represents a propyleneoxy group. HO-(EO)x1-(PO)y1-(EO)x2-H (2)

[0022] In formula (2), the chain block of ethyleneoxy groups represented by (EO)x1, the chain block of propyleneoxy groups represented by (PO)y1, and the chain block of ethyleneoxy groups represented by (EO)x2 are bonded in this order. x1 + x2 is preferably an integer of 11 to 170, more preferably an integer of 11 to 165, from the viewpoints of foamability and foam stability. y1 is preferably an integer of 18 to 35, more preferably an integer of 18 to 34, from the viewpoints of foamability and foam stability.

[0023] R 2 -(EO)x3 / (PO)y2-H (3)

[0024] In formula (3), in the poly(alkyleneoxy) group represented by (EO)x3 / (PO)y2, a total of x3 ethyleneoxy groups and a total of y2 propyleneoxy groups are randomly bonded. R 2is an alkyl group having 1 to 4 carbon atoms, x3 is preferably an integer of 11 to 108 from the viewpoints of foaming property and foam stability, y2 is preferably an integer of 5 to 81 from the viewpoints of foaming property and foam stability, and x3 / y2 is preferably 0.4 to 3.4 from the viewpoints of foaming property and foam stability.

[0025] In general formula (3), R 2 is the same as the alkyl group having 1 to 4 carbon atoms represented by R 1 in the general formula (1), and the preferred ones are also the same. In general formula (3), when R 2 is an n-butyl group, from the viewpoints of foaming property and foam stability, x3 is preferably an integer of 11 to 21, y2 is preferably an integer of 7 to 16, and x3 / y2 is preferably 1.3 to 1.6. When R 2 is an n-propyl group, from the viewpoints of foaming property and foam stability, x3 is preferably an integer of 17 to 108, y2 is preferably an integer of 5 to 81, and x3 / y2 is 1.3 to 3.4. When R 2 is a methyl group, from the viewpoints of foaming property and foam stability, x3 is an integer of 11 to 20, y2 is an integer of 10 to 30, and x3 / y2 is 0.4 to 2.0.

[0026] The ore slurry dehydration accelerator of the present invention contains 50 to 100% by weight of the ethylene oxide / propylene oxide copolymer based on the total weight of the dehydration accelerator. The content of the ethylene oxide / propylene oxide copolymer is preferably 70 to 100% by weight, more preferably 100% by weight, based on the total weight of the dehydration accelerator. If it is less than 50% by weight, the addition amount of the dehydration accelerator to the ore slurry becomes too large.

[0027] When the content of the copolymer is less than 100% by weight, the dehydration accelerator preferably contains a diluent (such as propylene glycol and water) as a component other than the copolymer. The content of the diluent is preferably 50% by weight or less, more preferably 30% by weight or less, based on the total weight of the dehydration accelerator from the viewpoint of the addition amount of the copolymer.

[0028] In addition, the dehydration accelerator of the present invention may contain known additives (such as preservatives) added to aqueous agents as components other than the copolymer as long as the effects of the invention are not inhibited. From the viewpoints of safety and dehydration performance, the content of the additive is preferably 1% by weight or less based on the total weight of the dehydration accelerator.

[0029] In the dehydration accelerator for ore slurry of the present invention, examples of the ore contained in the ore slurry include iron ore, copper ore, nickel ore, and coal ore.

[0030] The copolymer of the present invention is relatively low in toxicity. Although it is assumed that the dehydration treatment using the dehydrating agent for ore slurry may be carried out outdoors or the water contained in the slurry may be discharged into the environment, even when used in such cases, the environmental load can be kept low.

[0031] <Method for producing dehydration accelerator> The dehydration accelerator of the present invention can be produced by stirring the copolymer, a diluent and other components used as required in a mixing tank equipped with a stirrer and a heating and cooling device at preferably 20 to 60 °C until uniform. There is no limitation on the order of adding the copolymer, the diluent and other components used as required to the mixing tank. However, when using a diluent, it is preferable to add the copolymer and other components used as required to the diluent.

[0032] <Method for using dehydration accelerator> The dehydration accelerator of the present invention exerts the effect of promoting dehydration from the ore slurry by adding it to the ore slurry to be dehydrated by any method. For example, the dehydration accelerator of the present invention can be added to the ore slurry so that the ethylene oxide / propylene oxide copolymer is contained at a concentration of 0.05 to 1% by weight (preferably 0.1 to 0.5% by weight) based on the weight of the water contained in the ore slurry. The addition of the dehydration accelerator to the ore slurry may be carried out in the slurry storage tank or in the transfer line during the transfer of the ore slurry to the slurry storage tank or the dehydration device. Further, as the dehydration method of the ore slurry, known methods such as gravity filtration, suction filtration, filter press, and centrifugal dehydration can be used.

[0033] The ethylene oxide / propylene oxide copolymer contained in the drainage separated from the ore slurry by the dehydration operation can be separated and recovered from the drainage by utilizing its cloud point. As a method for recovering the copolymer from the drainage, the drainage is heated to a temperature exceeding the cloud point of the copolymer, and further centrifuged to separate the aqueous layer containing the copolymer and the aqueous layer not containing the copolymer, and the copolymer can be recovered by recovering the aqueous layer containing the copolymer. The recovered aqueous layer containing the copolymer can be reused as a dehydration accelerator.

Examples

[0034] Hereinafter, the present invention will be described in detail by way of examples, but the present invention is not limited thereto.

[0035] <Production of Copolymer> <Production Example 1> Into an autoclave equipped with a stirrer, a thermometer, a pressure gauge, a pressure-resistant dropping cylinder, and a vacuum and nitrogen introduction line, 76 parts by weight (1 mol part) of propylene glycol as a starting material and 2.6 parts by weight of potassium hydroxide as a reaction catalyst were charged, and then stirring was started. While introducing nitrogen into the autoclave under stirring, it was heated to 120°C. When it reached 120°C, the pressure was reduced (pressure -0.1 MPaG), and the autoclave was dehydrated by maintaining the same conditions for 1 hour. Then it was heated to 130°C, and 1798 parts by weight (31 mol parts) of propylene oxide as an additional raw material was sequentially dropped from the pressure-resistant dropping cylinder so that the pressure in the autoclave was maintained at 0.3 MPaG or less at 130°C. After dropping the total amount of propylene oxide, stirring at the same temperature was continued until the pressure in the autoclave became balanced. When the pressure reached equilibrium, 616 parts by weight (14 mol parts) of ethylene oxide as another additional raw material was sequentially dropped from the pressure-resistant dropping cylinder so that the pressure was maintained at 0.3 MPaG or less, and stirring at the same temperature was continued until the pressure became balanced. Then the autoclave was cooled to 60°C, 2.6 parts by weight of acetic acid was added to neutralize the catalyst, and ethylene oxide / propylene oxide copolymer 1 (hereinafter, copolymer 1) was obtained.

[0036] <Production Examples 2 to 7, Comparative Production Examples 1 and 3> Copolymers 2 to 7 according to Production Examples 2 to 7, and comparative copolymers H1 and H3 according to Comparative Production Examples 1 and 3 were obtained in the same manner as in Production Example 1, except that the amounts of propylene oxide and ethylene oxide used as additional raw materials in Production Example 1 were changed to the amounts shown in Table 1.

[0037] <Production Example 8> 74 parts by weight (1 mole part) of 1-butanol as a starting material and 0.1 part by weight of potassium hydroxide as a catalyst were charged into an autoclave equipped with a stirrer, a thermometer, a pressure gauge, a pressure-resistant dropping funnel, and a vacuum and nitrogen introduction line, and then stirring was started. While enclosing nitrogen in the autoclave under stirring, it was heated to 120°C. When it reached 120°C, the pressure was reduced (pressure -0.1 MPaG), and the autoclave was dehydrated by maintaining the same conditions for 1 hour. Then it was heated to 160°C, and a mixture of 924 parts by weight (21 mole parts) of ethylene oxide and 928 parts by weight (16 mole parts) of propylene oxide as additional raw materials was sequentially dropped from the pressure-resistant dropping funnel so that the pressure in the autoclave was maintained at 0.3 MPaG or less at 160°C, and stirring was continued at the same temperature until the pressure became balanced. Then the autoclave was cooled to 60°C, 0.3 part by weight of acetic acid was added to neutralize the catalyst, and an ethylene oxide / propylene oxide copolymer 8 (hereinafter, copolymer 8) was obtained.

[0038] <Production Examples 9 to 13, Comparative Production Examples 2 and 4> In Production Example 8, except that the starting materials and additional raw materials were changed to the amounts of the respective starting materials and additional raw materials described in Table 1, copolymers 9 to 13 according to Production Examples 9 to 13, and comparative copolymers H2 and H4 according to Comparative Production Examples 2 and 4 were obtained in the same manner as in Production Example 8.

[0039] The compositions and physical properties of copolymers 1 to 13 obtained in Production Examples 1 to 13 and comparative copolymers 1 to 4 obtained in Comparative Production Examples 1 to 4 are shown in Table 1. In Table 1, the numbers described in the columns of the starting materials and additional raw materials are the usage amounts of the respective raw materials, the numbers outside the parentheses represent parts by weight, and the numbers inside the parentheses represent mole parts.

[0040] The cloud points of copolymers 1 to 13 and comparative copolymers H1 to H4 described in Table 1 were measured by the following method. <Method for Measuring Cloud Point> For each of the copolymers 1 to 13 and the comparative copolymers H1 to H4, an aqueous solution of 1% by mass of the copolymer was prepared and used as a measurement sample. After putting the measurement sample into a test tube up to a height of about 40 mm, a thermometer was inserted into it, and heating was gradually carried out while stirring with the thermometer. When the aqueous solution became cloudy, heating was stopped when it was heated to a temperature 2 to 3 °C higher than the temperature at which cloudiness occurred. After stopping the heating, it was air-cooled while stirring well, and stirring was continued until the aqueous solution became transparent, and the temperature (°C) of the thermometer when it became transparent was defined as the cloud point.

[0041]

Table 1

[0042] <Production of dehydration accelerator> (Examples 1 to 13 and Comparative Examples 1 to 4) Each of the copolymers obtained in Production Examples 1 to 13 and Comparative Production Examples 1 to 4 was used as dehydration accelerators 1 to 13 and comparative dehydration accelerators H1 to H4 as they were, and for each of them, a dehydration test, a foaming property test, and a foam stability test were carried out. The results of each are shown in Table 2.

[0043] (Examples 14 to 15 and Comparative Example 5) Into a mixing tank equipped with a stirrer and a heating and cooling device, the copolymer in the parts by weight described in Table 2 and propylene glycol (manufactured by Fujifilm Wako Pure Chemical Corporation), which is a diluent, were charged, and stirred and mixed at 40 °C for 15 minutes to obtain dehydration accelerators 14 and 15 according to Examples 14 and 15 and a comparative dehydration accelerator H5 according to Comparative Example 5, respectively. For each of them, a dehydration test, a foaming property test, and a foam stability test were carried out, and the results are shown in Table 2.

[0044] <Dehydration test> 120 g of water and 40 g of fine iron ore were mixed to prepare an iron ore slurry for dehydration test (total weight: 160 g). 0.12 g each of dehydration accelerators 1 to 15 and comparative dehydration accelerators H1 to H5 were added to the iron ore slurry to obtain a slurry for dehydration test. Next, the entire amount of the slurry for dehydration test was placed in a Buchner funnel with an inner diameter of 8 cm lined with a quantitative filter paper (No. 5B) with a diameter of 7 cm, and dehydration was carried out by immediately sucking at a pressure of 25 kPa for 30 seconds. The weight of the ore cake remaining in the funnel was measured and taken as the weight of the ore cake before drying. Thereafter, the entire amount of the ore cake was dried by heating at 130°C for 1 hour, the weight of the ore cake after drying was measured, and the moisture content of the ore cake after dehydration was calculated using the following formula. A lower moisture content means a higher dehydration effect. It is good when the moisture content is 9.0% or less. Moisture content of the ore cake after dehydration (%) = (Weight of the ore cake before drying - Weight of the ore cake after drying) (g) ÷ (Weight of the ore cake before drying) (g) × 100

[0045] <Foaming property test> An aqueous solution with a concentration of 0.1 wt% obtained by diluting each of dehydration accelerators 1 to 15 and comparative dehydration accelerators H1 to H5, which were temperature-controlled to 20°C, with ion-exchanged water was used as a test solution, and evaluated according to the measurement methods of foaming power and foam stability described in JIS K3362:2008 Test methods for synthetic detergents for household use. Specifically, in a test environment at 20°C, 200 mL of the test solution placed in a dropping pipette A was dropped onto the liquid surface of 50 mL of the test solution placed in a cylinder from a height of 900 mm within 30 seconds, and the foam height was measured immediately after the dropping was completed. A lower foam height indicates lower foaming property. It is good when the foam height is 35 mm or less, indicating low foaming property.

[0046] <Foam stability test> The foam height was measured 5 minutes after pouring 200 mL of each test solution in the foaming property test. A lower foam height means that the generated foam disappears faster, indicating lower foam stability. It is good when the foam height is 14 mm or less, indicating low foam stability.

[0047]

Table 2

[0048] As shown in Table 2, all of the dehydration accelerators in the examples had a high dehydration effect and both low foaming properties and foam stability. On the other hand, among the dehydration effect, foaming properties, and foam stability of the comparative dehydration accelerators, at least one of the evaluation results was inferior.

Industrial Applicability

[0049] Since the dehydration accelerator of the present invention has a high dehydration effect and low foaming properties and foam stability, it can be preferably used for the dehydration of ore slurries transported in slurry form.

Claims

1. A dehydration promoter for ore slurries, comprising an ethylene oxide / propylene oxide copolymer represented by the following general formula (1): The number average molecular weight of the copolymer is 900 to 10,000; the total weight ratio of ethyleneoxy groups based on the total weight of the copolymer is 21% by weight to 85% by weight; A dehydration promoter for ore slurry, comprising the copolymer in an amount of 50 to 100% by weight based on the total weight of the dehydration promoter. R １ --(AO)--+ (1) "In formula (1), R １ represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, (AO)n represents a poly(alkyleneoxy) group consisting of 11 or more ethyleneoxy groups and one or more propyleneoxy groups, and the bonding order of the ethyleneoxy groups and propyleneoxy groups constituting the poly(alkyleneoxy) group may be random or block.

2. The dehydration promoter according to claim 1, wherein the ratio [x / y] of the number of moles of ethyleneoxy groups (x) to the number of moles of propyleneoxy groups (y) contained in the ethylene oxide / propylene oxide copolymer is 0.4 / 1 to 3 / 1.

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