Flotation reagents from acidic olive oil

Abstract

The flotation reagents from acidic olive oil are made by transesterification of acidic olive oil. Acidic olive oil is olive oil having an acid value high enough to render it unsuitable for consumption, typically greater than 3.3% and/or between 3.3-7%. Transesterification of the olive oil with methanol converts fatty acids in the olive oil to an ester fraction and a glycerol fraction. The ester fraction may be sulfonated and used as the collector in a reverse flotation process, selectively removing the carbonate gangue from phosphate-carbonate rock in the froth, leaving phosphates in the sink. The glycerol fraction may be used without modification as the collector in the reverse flotation process. Both fractions are highly selective for carbonates, substantially reducing loss of phosphates in the froth.

Claims

1. A flotation reagent from acidic olive oil, comprising: a mixture of esters of fatty acids contained in the acidic olive oil from transesterification of the acidic olive oil with methanol in presence of a base, wherein the mixture of esters is sulfonated.

2. The flotation reagents from acidic olive oil according to claim 1, wherein the acidic olive oil is at least 3.3% acid, the acidic olive oil being waste olive oil not suitable for human consumption.

Description

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(1) The flotation reagents from acidic olive oil may be made by transesterification of acidic olive oil. According to the Food and Agricultural Organization of the United Nations (FAO)—Codex Standard for Olive Oil, Virgin and Refined and for Refined Olive-Pomace Oil (CODEX STAN 33-1981, Rev. 1-1989) in Section 3.2.2 of the FAO, the maximum percent acidity (acid value) allowed for any type of olive oil is 3.3. Any acid value above 3.3% renders the olive oil unsuitable for human consumption. For use in making the flotation reagents described herein, the acidic value may be greater than 3.3% and/or between 3.3-7%. In a particular embodiment, the acidic olive oil has an acid value of about 5%. The acidic olive oil may comprise a combination of unsaturated and saturated fatty acids. For example, the acidic olive oil may include, by volume, 25-100% unsaturated fatty acids and 0-75% saturated fatty acids. The acidic olive may contain, e.g., about 80% unsaturated fatty acids and about 20% saturated fatty acids. The major fatty acids in the waste acidic olive oil are typically oleic acid, palmitic acid, linoleic acid, stearic acid, linolenic acid, palmitoleic acid, eicosenoic acids and unsaturated derivatives thereof. An exemplary acidic olive oil may include about 66% oleic acid, about 17% palmitic acid and about 11.5% linoleic acid.

(2) The collector is made by transesterification of the waste acidic olive oil. The transesterification may be performed using methanol in the presence of a base as catalyst. The results of transesterification are separated into two fractions, including a top fraction and a bottom fraction, by density, i.e., by sedimentation, demixing, centrifugation, or any other known means of separating transesterification products. The top fraction (which comprises product esters) and the bottom fraction (which comprises product glycerides) may each be used as collectors for the reverse flotation of phosphate ore.

(3) The collectors synthesized from acidic olive oil are more selective than previously used collectors, resulting in a better grade, yield and recovery of the phosphate ores.

(4) The collector for the separation of carbonates by flotation from phosphate ores may be synthesized by the transesterification of low acidic olive oil with methanol in the presence of a base as catalyst.

(5) The collector may be one of the at least two fractions resulting from separation of the products of transesterification of acidic olive oil with methanol in the presence of a base catalyst, in particular, a top fraction and a bottom fraction. The bottom fraction may be used as the collector for carbonates by flotation from phosphate ores. The bottom fraction may be used in combination with fuel oil (e.g., kerosene or diesel oil) as collector for the carbonates by flotation from the phosphate ores.

(6) The top fraction may be sulfonated and used as collector for calcite by flotation from the phosphate ores.

(7) The top fraction may be sulfonated and combined with fuel oil to be used as the collector for carbonates by flotation from the phosphate ores.

(8) A process for the separation of carbonates present in phosphoric rock by flotation includes the following. Ground phosphate-carbonate rock is mixed with water to form a slurry, the slurry is conditioned with the collector and other surfactants to form a chemically conditioned slurry, the chemically conditioned slurry is aerated to produce a foam, and the foam is separated along with the carbonates attached to the froths, leaving phosphates as a flotation residue.

(9) The process may proceed as above using from 1 to 20 kg of the collector per ton of raw phosphoric rock used.

(10) The collector has high flotation efficiency for calcite and has no affinity for apatite/francolite minerals.

(11) The collector has high flotation efficiency for phosphate ore by yielding high-grade concentrates from a feed ore. The collector may also allow for reduced phosphates contained in a froth phase in a phosphate ore flotation.

(12) The mineral beneficiation process uses froth flotation. The process removes calcite and other gangue, for example, iron-bearing minerals, magnesite, and silicates in a froth phase using the collector.

(13) Froth flotation is a physicochemical process for recovering a valuable or desired mineral present in an ore. Several factors affect the froth flotation process, such as the desired mineral's characteristics, particle size, and particle liberation; pH of the slurry (mixture of ore solvents (typically water) to which reagents are added in a flotation process); a choice of collector, frother, and depressant; and a dosage of each element used. In the flotation process, the gangue minerals are depressed (lowered to the bottom of the flotation vessel) by using a depressant. The target mineral is selectively made hydrophobic by using the collector. The pH of the slurry is chosen to optimize adsorption of the collector on the target mineral only. After chemical conditioning, bubbles are generated by introducing air into the slurry system of the finely divided ore (aeration). The collector adhering to the target mineral renders the target mineral hydrophobic, changing the mineral's affinity for the air bubbles. After particle attachment, the bubbles rise to the top as a froth phase. The hydrophilic wetted mineral remains in the slurry and is discarded at the bottom. However, in the case of reverse flotation, the valuable mineral is depressed, while the gangue minerals are selectively made hydrophobic for removal in the froth phase during aeration.

(14) Collectors are essential reagents used in a flotation process to recover or discard a mineral present in ore. The collector must selectively adsorb onto the target mineral (in flotation, it is the valuable mineral while in case of reverse flotation, it is the gangue mineral) even with the presence of many other similar mineral types. Flotation theory suggests that the one mineral type separates from another mineral based on their relative surface wettability. The collectors used in the flotation process to treat the ore are heteropolar surface-active agents. They lower the surface energy of the mineral by adsorbing onto its surface. The polar part adsorbs onto the particle surface, while the non-polar group orients to the bulk of the solution, thus facilitating a bridge for bubble attachment with the particle. However, the present reagents are not limited to flotation theory.

(15) There are reagents available for the recovery of phosphate from the phosphate rock. However, they are not suitable for certain phosphate ores, such as the Al-Jalameed type phosphate ores (Table 1) found in Saudi Arabia. Therefore, there is a need to develop a collector that will provide increased recovery of phosphorous values with high-grade concentrate and reduce the loss of phosphate in the flotation tailings. A large quantity of phosphate rock has been processed by using the froth flotation system. The improved collector can result in a considerable increase in the recovery of the total quantity of phosphorus oxide. It will provide substantial economic advance, even with a modest increase in recovery. Thus, an improved process for froth flotation of oxide and carbonate minerals would fulfil a long-felt need and constitute a notable advancement in the art. Besides, the reagents currently being employed are derived from edible vegetable oils. Thus, the provision of utilizing non-edible waste oils, by itself, is a significant contribution to the art. Also, the improved developed reagent is a green surfactant, as it derived from a green resource.

(16) In conjunction with the present reagents, a process is also provided for recovering phosphate minerals, which comprises crushing, grinding, and/or classification of the mineral to produce desired particle sizes for the flotation process; slurrying the liberated mineral in an aqueous medium; conditioning the slurry with optimum reagent dosage; and floating the gangue by reverse froth flotation method. A depressant may be added to the phosphate mineral. For example, phosphoric acid may be used as a depressant for phosphate minerals in the slurry. The phosphoric acid may be used in the range of 5-20 g/kg of phosphate ore. The pH may be adjusted to 2-8, 3-7, 4-6 or 5-6. The pH may be adjusted by addition of sulfuric acid, for example, in the range of 5-22 g/kg of phosphate ore. These surfactants may be either adsorbed onto the mineral or remain in the solution. A frother may be added to aid in the formation and maintenance of froth at the top of the flotation vessel. For example, pine oil may be used as a frother. Aeration may be performed by maintaining an air rate in the range of 2-6 L/min for aeration in the flotation cell.

(17) Use of the collectors provides good recovery of valuable minerals at high grade or purity levels under normal froth flotation conditions. These reagents do not present excessive foaming problems. The collectors are synthesised by utilizing waste acidic olive oil and esterifying agents, such as methanol.

(18) It should be understood that the amounts of materials for the methods described herein are exemplary, and appropriate scaling of the amounts is encompassed by the present subject matter, so long as the relative ratios of materials are maintained. As used herein, the term “about,” when used to modify a numerical value, means within ten percent of that numerical value.

(19) Flotation reagents, i.e., frothers, depressants, modifiers, and other collectors, may be substituted or added in the above flotation methods. Frothers may be any known substance that acts to stabilize the foam, such as pine oil, various alcohols (methyl isobutyl carbinol (MIBC)), polyglycols, xylenol (cresylic acid), etc. Depressants or inhibitors prevent floatation of certain minerals other than the mineral to be floated, and may include organic or inorganic depressants. Common organic depressants include starch and glue and common inorganic depressants include, for example, lime, sodium sulfite, sodium silicate, cyanide, and dichromate. Modifiers may be added to adjust any desired property during flotation, such as sulfurization, pH, viscosity, etc.

(20) The present disclosure is illustrated by the following examples.

Example 1

Exemplary Collector Synthesis

(21) An exemplary collector for the separation of carbonates from phosphate ores by froth flotation was synthesized by transesterification of acidic olive oil. The acidic olive oil had an acid value of 5.14%, not suitable for human consumption. It contained 79.9% unsaturated fatty acids, and 20.1% saturated fatty acids. The major fatty acids in the waste acidic olive oil were oleic acid—66.25%; palmitic acid—17.37%; and linoleic acid—11.51%. The transesterification products of the waste acidic olive oil were separated into two fractions by sedimentation. The top fraction (esters) and a bottom fraction (glycerides) were used as collectors for the reverse flotation of the phosphate-carbonate ore. The reverse flotation of the phosphate ore was successfully achieved using the glycerides of the transesterification product. The new collectors synthesized from acidic olive oil are more selective than previously used collectors, resulting in a better grade, yield, and recovery of the phosphate ores.

Example 2

Exemplary Flotation and Reverse Flotation Processes

(22) In a flotation process, the crushed ore was deslimed to remove particles less than 38 μm in size. In the laboratory, desliming was performed by wet sieving. However, in industrial-scale processes, desliming is typically performed by using a hydrocyclone. The exemplary collectors were used as a collector for carbonates by flotation, as shown in Tables 2-3. The phosphate minerals (e.g., francolite) were depressed in the flotation process with H.sub.3PO.sub.4 (10%, v/v) and H.sub.2SO.sub.4 (20%, v/v) as follows. A slurry was formed from an aqueous solution with phosphate ore prepared as above, where the slurry was prepared to have 20% (w/w) solid phosphate ore in aqueous solution. Phosphoric acid (H.sub.3PO.sub.4) was added to the slurry to a concentration of 10% v/v, and the ore in the slurry was conditioned for 30 sec. After that, sulfuric acid (H.sub.2SO.sub.4) was added to the slurry to a concentration of 20% v/v, and the slurry was conditioned for a further 30 sec. The collector was added after depression of the phosphate minerals, and the ore in the slurry was conditioned for one minute. Pine oil was used as a frother. After conditioning of the phosphate ore with the flotation reagents, the slurry was aerated. On aeration, bubbles are generated and the hydrophobic carbonates attach to the bubbles and rise to the top, where they are collected as froth. After completion of the flotation process, the remaining froth and sink were allowed to settle, and water was removed by decantation. The residual froth and sink were each dried in an oven. The dried froth and sink were weighed and analyzed for P.sub.2O.sub.5 using X-ray fluorescence (XRF).

(23) The collector was used alone for the flotation of calcite from a calcite-apatite mineral system. Collector selectivity was enhanced for some applications when used in combination with fuel oil, such as diesel, kerosene, etc. (see Tables 3-4), particularly for the collector selected from the bottom fraction. The ratio of synthesized surfactant and diesel oil should be in the range of 50:50-70:30, depending on the characteristics of the phosphate ore and desired mineral. Fuel oil alone is not an effective collector, but only enhances the efficiency of the present collector.

(24) The phosphate ores used in the present examples are Saudi Al-Jalameed phosphate ores that have the following composition (Table 1):

(25) TABLE-US-00001 TABLE 1 Exemplary phosphate-carbonate ore composition Name of Element % of element present in bulk Sample P.sub.2O.sub.5 22.61 MgO 2.90 SiO.sub.2 1.19 CaO 49.59 Al.sub.2O.sub.3 0.29 Fe.sub.2O.sub.3 0.16

(26) Existing collectors are inefficient in the selective flotation of the calcite ore. The froth phase produced using such collectors typically have 10-12% P.sub.2O.sub.5. The present collectors have improved efficiency, resulting in 6% P.sub.2O.sub.5 in the froth phase. The present collector has better selectivity to calcite ore than existing collectors.

(27) TABLE-US-00002 TABLE 2 Composition of the exemplary acidic olive oil Limit of Test Unit Amount detection Method ref. Palmitic acid Rel. % 17.37 0.01 AOAC-996.01 C.sub.16H.sub.32O.sub.2 Palmitoleic acid Rel. % 1.45 0.01 AOAC-996.01 C.sub.16H.sub.30O.sub.2 Stearic acid Rel. % 2.41 0.01 AOAC-996.01 C.sub.18H.sub.36O2 Oleic acid Rel. % 66.25 0.01 AOAC-996.01 C.sub.18H.sub.34O.sub.2 Linoleic acid Rel. % 11.51 0.01 AOAC-996.01 C.sub.18H.sub.32O.sub.2 Eicosanoic (arachidic) Rel. % .32 0.01 AOAC-996.01 acid C.sub.20H.sub.40O.sub.2 Linolenic acid Rel. % .52 0.01 AOAC-996.01 C.sub.18H.sub.30O.sub.2 11-eicosanoic acid Rel. % .17 0.01 AOAC-996.01 C.sub.20H.sub.38O.sub.2 Saturated fatty acid % 20.10 0.01 AOAC-996.01 Unsaturated fatty acid % 79.90 0.01 AOAC-996.01 Monounsaturated fatty % 67.87 0.01 AOAC-996.01 acid Polyunsaturated fatty acid % 12.03 0.01 AOAC-996.01 Trans fatty acid % 0.00 0.01 AOAC-996.01

(28) Table 2 summarizes the main components of the acidic olive oil used in synthesizing the present exemplary collectors. The acidic olive oil need not have the specific composition of table 2.

Example 3

Flotation of Saudi Al-Jalameed Phosphate Ores

(29) Using the bottom fraction as the collector, the Saudi Al-Jalameed phosphate ore was processed according to the general procedure described above. The flotation experimental conditions were varied according to the parameters in Table 3 to illustrate their effect on the grade and recovery of the P.sub.2O.sub.5. Table 3 shows of the experimental results.

(30) Using the bottom fraction collector with fuel oils, the Saudi Al-Jalameed phosphate ore was processed according to the general procedure described above. The following flotation experimental conditions were maintained:pH—5.2-5.5, RPM—900, Air Rate—5 l/m, depressant—15.30 g/Kg, 10% H.sub.3PO.sub.4 and 16.67 g/Kg, 20% H.sub.2SO.sub.4. Table 4 shows the experimental results.

(31) TABLE-US-00003 TABLE 3 Experimental flotation results - Collector without fuel oil Impeller Air H.sub.3PO.sub.4 H.sub.2SO.sub.4 Sink Sink Froth Froth Feed P.sub.2O.sub.5 Collector, speed, rate, Frother (10%, v/v) (20%, v/v) Yield, P.sub.2O.sub.5, Yield, P.sub.2O.sub.5, P.sub.2O.sub.5, Recovery, Sl. No. g/kg ore rpm l/m g/kg g/kg g/kg pH % % % % % % 1 11.96 900 5 0.46 15.30 16.67 5.2-5.5 73.66 23.26 26.34 6.13 18.75 91.37 2 14.35 900 5 0.46 15.30 16.67 5.2-5.5 62.60 27.03 37.4 9.52 20.49 82.61 3 14.83 900 5 0.46 15.30 16.67 5.2-5.5 54.80 30.79 45.20 10.05 21.42 78.79 4 15.31 900 5 0.46 15.30 16.67 5.2-5.5 30.19 31.24 69.81 15.41 20.19 46.71 5 14.83 600 5 0.46 15.30 16.67 5.2-5.5 57.49 32.09 42.51 8.36 22.00 83.84 6 14.83 700 5 0.46 15.30 16.67 5.2-5.5 56.60 31.47 43.40 7.14 20.91 85.17 7 14.83 800 5 0.46 15.30 16.67 5.2-5.5 56.71 30.52 43.29 8.12 20.82 83.12 8 14.83 900 5 0.46 15.30 16.67 5.2-5.5 56.21 32.67 43.29 8.12 22.26 82.52 9 14.83 1000 5 0.46 15.30 16.67 5.2-5.5 46.47 31.53 53.53 12.76 21.49 68.20 10 14.83 700 2 0.46 15.30 16.67 5.2-5.5 61.28 30.19 38.72 6.64 21.08 87.79 11 14.83 700 3 0.46 15.30 16.67 5.2-5.5 55.54 32.60 44.46 7.96 21.65 83.67 12 14.83 700 4 0.46 15.30 16.67 5.2-5.5 54.28 32.35 45.72 9.19 21.77 80.68 13 14.83 700 5 0.46 15.30 16.67 5.2-5.5 52.06 30.94 47.94 11.29 21.52 74.85 14 14.83 700 6 0.46 15.30 16.67 5.2-5.5 48.35 31.84 51.65 11.18 21.17 72.72 15 14.83 700 3 0.00 15.30 16.67 5.2-5.5 59.23 29.04 40.77 6.47 19.84 86.70 16 14.83 700 3 0.11 15.30 16.67 5.2-5.5 59.01 29.46 40.99 6.87 20.20 86.06 17 14.83 700 3 0.23 15.30 16.67 5.2-5.5 59.10 30.38 40.90 6.61 20.66 86.90 18 14.83 700 3 0.46 15.30 16.67 5.2-5.5 55.54 32.60 44.46 7.96 21.65 83.63 19 14.83 700 3 0.68 15.30 16.67 5.2-5.5 56.94 28.35 43.06 7.30 19.24 83.70 20 14.83 700 3 0.91 15.30 16.67 5.2-5.5 59.66 29.71 40.34 7.20 20.63 85.91 21 14.83 700 3 0.46 10.20 16.67 5.2-5.5 63.59 30.57 36.41 6.40 21.77 89.29 22 14.83 700 3 0.46 15.30 16.67 5.2-5.5 62.72 30.90 37.28 6.31 21.74 89.17 23 14.83 700 3 0.46 20.40 16.67 5.2-5.5 62.43 31.14 37.57 5.37 21.59 90.03 24 14.83 700 3 0.46 15.30 16.67 4.5-4.8 72.93 28.34 27.07 5.92 22.27 92.81 25 14.83 700 3 0.46 15.30 16.67 5.2-5.5 63.02 30.15 36.98 6.63 21.45 88.58 26 14.83 700 3 0.46 15.30 16.67 5.7-6.0 69.48 27.42 30.52 8.37 21.61 88.17 27 14.83 700 3 0.46 15.30 16.67 6.2-6.5 45.61 26.86 54.39 15.46 20.66 59.31 28 14.83 700 3 0.46 15.30 16.67 5.2-5.5 60.65 31.35 39.35 6.45 21.55 88.23

(32) TABLE-US-00004 TABLE 4 Experimental flotation results - Collector combined with fuel oil % % P.sub.2O.sub.5, % P.sub.2O.sub.5, Sl. Collector Diesel Frother Froth Wt. Conc. Wt. % P.sub.2O.sub.5, % P.sub.2O.sub.5, % P.sub.2O.sub.5, recovery to recovery to No. g/kg g/kg g/kg % % Head Froth Conc. froth conc. 1 22.2 8.32 0.46 25.90 74.10 24.11 16.36 26.82 17.57 82.43 2 22.2 16.64 0.46 28.61 71.39 24.60 15.29 28.33 17.78 82.22 3 37.0 8.32 0.46 29.07 70.93 24.47 12.50 29.38 14.85 85.15 4 37.0 16.64 0.46 36.40 63.60 24.57 13.83 30.71 20.50 79.50 5 37.0 16.64 0.46 34.26 65.74 24.00 10.87 30.85 15.52 84.48 6 37.0 16.64 0.46 30.54 69.46 25.37 12.73 30.93 15.32 84.68 7 37.0 24.96 0.46 32.38 67.62 22.80 11.18 28.36 15.88 84.12 8 37.0 31.20 0.46 29.76 70.24 24.31 10.41 30.20 12.74 87.26 9 46.9 39.52 0.46 26.57 73.43 23.53 16.10 26.22 18.18 81.82

(33) It is to be understood that the flotation reagents from acidic olive oil are not limited to the specific embodiments described above, but encompasses any and all embodiments within the scope of the generic language of the following claims enabled by the embodiments described herein, or otherwise shown in the drawings or described above in terms sufficient to enable one of ordinary skill in the art to make and use the claimed subject matter.