AU2013101186A4 - Composition and method for suppression of dust - Google Patents

Abstract

Abstract Provided herein are compositions for suppressing dust comprising an aqueous solution of lignosulfonate and sulfosuccinate ester. Also provided herein are method for suppressing dust by applying said compositions to dust producing materials.

Description

COMPOSITION AND METHOD FOR SUPPRESSION OF DUST Field The invention relates to the suppression of dust using an aqueous composition of specific anionic surfactants and to the composition for use in dust suppression. 5 Background Dust poses a health and safety risk which is of particular concern in mining operations. Finely divided ores and minerals generate dust during operations such as mining, ore crushing, transport and use. Water is used to reduce dust by periodically 10 applying a water spray to dust producing materials. The labour and equipment for regular wetting of surfaces produces high ongoing costs. Mines and mining operations are often in remote and arid regions and dust control represents one of the principle uses of water resources. For example, around 50% of 15 the water in Harding Dam, the principal reservoir for Karratha, Port Hedland servicing iron ore export from the Pilbara region of Western Australia, is used for dust control (Michael Mills, "Wasting water on dust control" Australian Mining, 15 September 2010). 20 Speciality polymers, such as acrylates or other polymers, have been used but many are relatively expensive or require relatively high use rates. Summary We have found that the combination of a lignosulfonate and sulfosuccinate ester 25 provides a readily available source of raw materials and cost effective dust suppression. Accordingly, there is provided a method of suppression of dust from a dust producing material comprising applying to the material an aqueous solution comprising a 30 lignosulfonate and sulfosuccinate ester (preferably selected from monoalkyl sulfosuccinates, dialkyl sulfosuccinates and mixtures thereof). 1 3174910.2 In a further aspect, there is provided a composition for suppressing dust comprising an aqueous solution of a lignosulfonate and sulfosuccinate ester (preferably selected from monoalkyl sulfosuccinates and dialkyl sulfosuccinates). 5 In a further set of embodiments, there is provided a method of preparing a composition for dust suppression comprising dissolving the lignosulfonate in water preferably at a temperature in the range of 300C to 600C to form a lignosulfonate solution; dissolving sulfosuccinate ester in the lignosulfonate solution, the sulfosuccinate ester 10 being selected from monoalkyl sulfosuccinates and dialkyl sulfosuccinates; and optionally adding further components Throughout the description and the claims of this specification the word "comprise" and variations of the word, such as "comprising" and "comprises" is not intended to 15 exclude other additives, components, integers or steps. Detailed Description The invention provides a method and composition for the suppression of dust in dust producing material. The dust producing material may be of any type of material which 20 tends to generate dust from a surface of material or during processing storage and handling. Examples of dust producing material include unpaved road surfaces, mineral ores, absorbents, animal feed, granular or powdered agrochemicals such as fertilizers, pesticide compositions and the like. 25 The method and composition are particularly useful in suppression of dust in mining operations and storage, handling and transport of ore including unprocessed and processed ore. More specific examples of dust producing materials include underground mine surfaces, storage heaps of mined ore, ore to be processed in dust producing processes such as crushing, partly storage heaps and handling such as 30 prior to transport such as by road or container ships. Examples of dust suppression in and around mining sites and in ore handling include haul road dust suppression, blasting site dust suppression, stockpile dust suppression, dust suppression prior to 2 3174910.2 one or more of transfer, discharge and crushing, dust suppression of waste dumping, dust suppression of conveyor belt ore transfer and underground airborne dust suppression. 5 The method of the invention may involve application to all or part of the surface of the material. Generally, it is convenient to apply the dust suppression composition to the material by spraying, although this will depend on the nature of the material and the scale on which the composition is to be applied. 10 The composition for suppressing dust may be prepared in the form of an aqueous concentrate composition comprising the lignosulfonate and sulfosuccinate ester and used in that form or diluted shortly before or at the time of use. The composition comprises a lignosulfonate. Lignosulfonate is generally in the form 15 of a metal salt, particularly an alkali metal or alkaline earth metal salt such as a lithium, sodium, potassium or calcium lignosulfonate salt. Sodium lignosulfonate, calcium lignosulfonate and mixtures thereof are particularly preferred. The composition comprises a sulfosuccinate ester which is preferably selected from 20 monoalkyl sulfosuccinates, dialkyl sulfosuccinate and mixtures thereof. The alkyl portion or portions of the sulfosuccinate ester are preferably C4 to C18 alkyl and more preferably C6 to C14 alkyl and still more preferably C6 to C12 alkyl. Accordingly, preferred monoalkyl sulfosuccinates are (C4 to C18 alkyl)sulfosuccinates, more preferably (C6 to C14 alkyl)sulfosuccinates, and still more preferably (C6 to C12 25 alkyl)sulfosuccinates. The preferred dialkyl sulfosuccinate is di(C 4 to C18 alkyl) sulfosuccinate, more preferably a di(C 6 to C14 alkyl) sulfosuccinate and still more preferably a di(C 6 to C12 alkyl) sulfosuccinate. Specific examples of monoalkyl sulfosuccinates include lauryl sulfosuccinate, laureth 30 sulfosuccinate, isodecyl sulfosuccinate, deceth-6 sulfosuccinate and laureth-9 sulfosuccinate. The monoalkyl esters are generally in the form of a dimetal salt, particularly as a dialkali metal salt such as with alkali metals selected from lithium,sodium and potassium. The disodium salt is particularly preferred. 3 3174910.2 Specific examples of dialkylsulfosuccinates may be selected from the group consisting of dibutyl sulfosuccinate, dihexylsulfosuccinate, dioctyl sulfosuccinate dicyclohexylsulfosuccinate, diisodecyl sulfosuccinate, bis-(2-ethylhexyl) 5 sulfosuccinate bis-(tridecyl)sulfosuccinate and mixtures of two or more thereof. The dialkyl sulfosuccinate may comprise an alkali metal counter ion such as lithium, sodium, potassium or mixtures thereof. Sodium salts are particularly preferred. Generally the dialkyl sulfosuccinates are the preferred sulfosuccinate ester. 10 The composition comprises a mixture of the lignosulfonate and sulfosuccinate ester. The weight ratio of lignosulfonate to sulfosuccinate ester is preferably in the range of from 1:10 to 10:1 and more preferably from 1:5 to 5:1. The concentration concentration lignosulfonate and sulfosuccinate in the composition 15 is not generally narrowly critical and will depend on the specific use and rate of application. Typically the total of lignosulfonate and sulfosuccinate ester will provide a concentration of 0.001% to 20% by weight of the composition. The composition may be prepared in the form of a concentrate for dilution before or at 20 the time of use. For example, in one embodiment, the composition is prepared as a concentrate comprising from 1% to 10% by weight of lignosulfonate and from 1% to 10% by weight of sulfosuccinate ester. The concentrate composition may, in one embodiment, be diluted to provide a total concentration of lignosulfonate and sulfosuccinate ester in the range of from 0.001% to 1% by weight of the composition 25 more preferably 0.01% to 0.5% by weight of the composition. The composition may if desired contain other components such as adjuvants selected from the group consisting of aromatics, dyes, polymers or the like. Polymers and/or additional dust suppressants may be included in the composition if desired, however 30 we have found that the composition of the invention is useful and economical in dust suppression if it is free of other dust suppressant components. Thus, it is generally preferred that the composition is free of polymers such as acrylates, methacrylates, free of bitumens and tar, and contains no more than 1% by weight of the composition, 4 3174910.2 preferably no more than 0.5% of the concentrate and no more than 0.001% of the dilute compositions of non-ionic surfactants. In one set of embodiments, the composition contains no more than 5% by weight 5 based on the weight of lignosulfonate and sulfosuccinate ester of non-ionic surfactant. The composition is an aqueous composition and generally water will make up at least 95%, preferably 97%, more preferably 98% by weight of components other than the lignosulfonate and sulfosuccinate ester. 10 In one set of embodiments, the concentrate composition comprises (on a weight basis): 1% to 10% lignosulfonate such as sodium lignosulfonate; 1% to 10% sulfosuccinate ester (preferably di-(C 6 to C12 alkyl) sulfosuccinate); 15 80% to 98% water; and 0% to 1% other components. In a further set of embodiments, the concentrate comprises (on a weight basis): 1% to 5% lignosulfonate; 20 1% to 5% sulfosuccinate ester (preferably dialkyl sulfosuccinate); 90% to 98% water; and 0% to 1% other components such as aromatics and colouring agents. As described above, the composition of the invention is particularly useful for dust 25 suppression in mining operations and in processing, storage and handling of mineral ores. The composition is particularly useful in suppression of dust associated with iron ore. The composition may be transported to the site of use as a concentrate and used in concentrated form or diluted prior to use or at the time of use. In one set of embodiments, the composition is applied to a dust producing material (for example a 30 mineral ore, such as iron ore) by spray apparatus known in the industry for producing a spray or fog of water based dust suppressant. The composition may be diluted prior to spraying or suitable equipment may be provided for continuously metering the composition into a spray apparatus. 5 3174910.2 The appropriate rate of spray application will depend on the conditions and extent of dust problem and extent of suppression of dust which is required. In one embodiment the composition is applied at a concentration in the range of from 0.001% of 5 combined weight of lignosulfonate and sulfosuccinate ester per volume of applied composition to 1% of combined weight of lignosulfonate and sulfosuccinate ester per volume of composition (i.e. from 0.001% w/v to 1 %w/v) The invention provides, in a further set of embodiments, a method of preparing a 10 composition for dust suppression the method comprising a method of preparing a composition for dust suppression comprising dissolving the lignosulfonate in water preferably at a temperature in the range of 300C to 600C to form a lignosulfonate solution; dissolving sulfosuccinate ester in the lignosulfonate solution; and 15 optionally adding further components. The invention will now be described with reference to the following examples. It is to be understood that the examples are provided by way of illustration of the invention and that they are in no way limiting to the scope of the invention. 20 6 3174910.2 EXAMPLES Example 1 A concentrate composition for dust suppression was prepared by mixing the following components in the percentage by weight specified in Table 1. 5 Table 1 Material % Weight Amount kg WATER 93.75 94 SODIUM LIGNOSULFONATE 2.00 2 *DOSS 70(S) 3.75 4 D-LIMONENE 0.50 1 46% NaOH SOLUTION As Required As Required TOTAL 100.00 100 *DOSS 70 contains 70% sodium di(2-ethylhexyl)sulfosuccinate which thus constitutes 2.63% by weight of the composition. 10 In preparing the composition, water was heated to 45-500C and the sodium lignosulfonate was added until fully dissolved. DOSS 70(s) was then added and mixed for 20 minutes followed by D-LIMONENE and the composition was mixed for a further 10 minutes. 15 The pH may of the composition may be adjusted using the sodium hydroxide solution, when necessary, to fall in the range 6.7 to 7.5. The composition is filtered through a 150 micron filter. The product may be used in this form or diluted significantly, for example, 1 litre of 20 composition diluted in from 1 to 500 litres of water. 7 3174910.2 Example 2 The composition of Example 1 was diluted at a rate of 1 litre of product in 100 litres of water and applied via a water cannon to an iron ore stock pile. This pile was turned numerous times via a wheel loader to assist in even coverage over the ore. On 5 crushing of this ore after application of product, there was almost no dust raised in the crushing process. In this application it was calculated that 1 litre of concentrated product of Example 1 in 100 litres of water treated 20 tonne of iron ore. Conditions at the mine were extremely dry with dust observed as very fine. 10 The diluted product may also be used in dust suppression using a water cannon to apply a mist or fog of aqueous solution to stock piles prior to or during transport shipping. Finally, it is understood that various other modifications and/or alterations may be 15 made without departing from the spirit of the present invention as outlined herein. 8 3174910.2

Claims (5)

1. A composition for suppressing dust comprising an aqueous solution of lignosulfonate and sulfosuccinate ester.

2. A composition for suppressing dust according to claim 1 wherein the sulfosuccinate is selected from di(C 6 to C12 alkyl) sulfosuccinate salts.

3. A composition for suppressing dust according to claim 1 or claim 2 wherein the total concentration of lignosulfonate and sulfosuccinate ester is in the range of 0.001% to 20%.

4. A composition for suppressing dust according to any one of claims 1 to 3, in the form of a concentrate comprising on a weight basis: 1% to 10% sodium lignosulfonate 1% to 10% di(C 6 to C12 alkyl) sulfosuccinate salt 80 to 98% water 0 - 1% other components.

5. A method of suppression of dust from a dust producing material comprising applying to the material an aqueous solution according to any one of the previous claims. 9

3174910.2