NL8204749A - METHOD FOR SEPARATING HYDROFILE SUBSTANCES FROM A HYDROFOOB MATERIAL - Google Patents

Description

F-—: 1 ................. ....... f, f "'* ........" * »N.0. 31,520 1

Method for separating hydrophilic substances from a hydrophobic material.

The present invention relates to a process for separating substances from a solid, wherein the substances have a different affinity for water than the pure solid, such as removing impurities from coal or removing gangue rocks from phosphates.

There are a variety of known techniques for removing impurities from solids based on the differences in properties between the pure solid and its impurities. For example, materials can be separated based on their size, their density, their ability to hold an electrical charge, or their magnetic properties. These methods are useful for most solids separation applications, but there are some solids which cannot be economically separated by this method because the pure solid and its impurities are too similar in these properties.

A solution to this problem is to use another property, such as affinity for water, to separate the solid from its impurities. According to a known method, ash (a hydrophilic impurity) is separated from coal (a hydrophobic solid) by forming a coal slurry, adding an oil to the slurry with mixing to produce agglomerates and removing the agglomerates as product. Most of the ash remains in the aqueous phase of the suspension.

An important drawback of this process is that the oil used to agglomerate the coal becomes part of the product. This means that they sell oil for the price of cabbage. This also means that this method could not be used to separate other hydrophobic materials from their hydrophilic impurities if oil were not a desirable part of the final product. It is possible to attempt to recover the oil from the agglomerates, but this would require extremely high temperatures (above 26 ° C) and even at these high temperatures the oil recovery will not be complete.

Pyrite-like sulfur is not usually removed by this method. The fuel oil contains components that activate the surface of both the carbon and the pyrite-like sulfur to make both 820 4 74 9 2 more hydrophobic, therefore the pyrite-like sulfur is agglomerated with the carbon.

Another method of separating two solids is by foam flotation. Foam flotation is a method of separating finely ground valuable minerals from their accompanying gangue. The method is based on the affinity of suitably prepared air bubble surfaces. A foam is formed by introducing air into a pulp of water-finely divided ore containing a flotation or foaming agent. Surface modifying reagents (collection agents) can also be added to increase the surface affinity of the mineral for air bubbles. Minerals with a specific affinity for air bubbles rise to the surface in the foam and are thus separated from the minerals wetted with water. As a first stage, the ore must first be ground to release its valuable mineral constituents therefrom from its worthless gangue matrix. The size reduction, usually to about 208 micrometers, reduces the minerals to such a particle size that they can be easily driven upward and floated by the bubbles.

Foam flotation can be used to produce a metallurgical grade carbon. In the foam flotation of bituminous coal, the fraction, which is rich in vitrinite, a component of carbon, with a low ash content and good coking properties, is most easily and quickly flotated. Vitrinite is the product needed to make a good metallurgical quality of coal. The remaining fraction has a high content of ash and pyrite-like sulfur. It would be advantageous if this ash and this pyrite-like sulfur could be removed from the remaining fraction.

It would also be advantageous if a separation method could achieve a better separation of two different solids than has been achieved with the prior art methods. It would also be advantageous if a separation method was more energy efficient than the prior art methods. It would also be effective if a separation method could separate two solids without agglomerating agent being present in the final product.

The present invention overcomes the drawbacks of the prior art by selective agglomeration of the hydrophobic material. In the present invention, an aqueous suspension is formed from the 820 4 74 9 W ~ 3 hydrophobic material and the hydrophilic materials; a non-polar water-insoluble coupling hydrocarbon is used to form agglomerates of the hydrophobic material and the agglomerates are separated from the suspension containing the hydrophilic substances. Preferably, the coupling hydrocarbon is recovered and recycled. An essential element of this invention is the coupling hydrocarbon used. It is essential that the coupling hydrocarbon has a low boiling point (70 ° C or less), such as butane, pentane, hexane and mixtures thereof.

In one embodiment of the present invention, the hydrophobic material and hydrophilic materials are ground in a suspension to have a particle size distribution of the hydrophobic material and hydrophilic materials, at least 90% of the particles being less than 10 micrometers in size and the agglomerates 15 are formed by subjecting the hydrophobic material, the hydrophilic substances and the coupling hydrocarbon to a strong shear agglomeration and a low shear agglomeration.

Preferably, the initial suspension of the hydrophobic material should contain from 10 to 20% by weight of solids and the separation step should be performed using a sieve or a centrifuge.

BRIEF DESCRIPTION OF THE DRAWINGS To facilitate understanding of the present invention, reference is made to the accompanying drawings of preferred embodiments of the present invention. The drawings are not to be construed as limiting the invention, but only as an example. In the drawings is:

Fig. 1 is a graphic showing the effect of agglomeration agent and particle size on the axis of a Pittsburgh Seam 30 carbon and

Fig. 2 a graphic showing the effect of the agglomerating agent on the sulfur from a Pittsburgh Seam coal.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the broadest sense, the present invention relates to separating hydrophilic materials from a hydrophobic material by forming an aqueous suspension of the hydrophobic material and hydrophilic materials, then selectively agglomerating the hydrophobic material. hydrophobic material agglomerates but not the hydrophilic substances. This selective agglomeration is carried out using a non-polar water-insoluble copper hydrocarbon 820 4 74 9% 4. After the selective agglomeration has taken place, the agglomerates can be separated by a sieve or a centrifuge and the coupling hydrocarbon can be recovered and recycled.

This method can be used to remove hydrophilic substances from hydrophobic materials or can be used to remove hydrophobic impurities from hydrophilic substances. When the impurities are hydrophilic, the end products are agglomerates of hydrophobic material and the slurry containing the hydrophilic impurities is a waste stream. When the impurities are hydrophobic, the final product is a suspension of hydrophilic substances that can be dried and the agglomerates of the hydrophobic material are waste.

In a particularly advantageous embodiment, oxidized or inferior carbon is mixed with water to form an aqueous suspension, in which carbon and the hydrophilic substances (ash and pyrite-like sulfur) are dispersed in water together with the carbon and the resulting suspension is 30 to 40 wt. % solids, the carbon in the slurry is ground so that the particle size distribution of the carbon has at least 90% of the particles smaller than 10 microns in size. Water is then added to the slurry to obtain a 10 to 20 wt% solids slurry, and pentane and fuel oil are added to the slurry with mixing so that the pentane is 30 to 40 wt% based on of pentane and dry coal and the fuel oil less than 5% by weight is based on dry coal and oil; the slurry is then subjected to both a high shear agglomeration and a low shear agglomeration to form agglomerates of the coal (the ash and pyrite-like sulfur remain dispersed in the slurry); the carbon agglomerates are then separated from the slurry by passing the slurry through a sieve, and the carbon agglomerates are heated in the absence of air to remove pentane, and then the pentane is recovered and recycled.

In another particularly advantageous embodiment, phosphate rock is mixed with water to form an aqueous suspension in which the phosphate rock and gangue minerals are dispersed in water and the resulting suspension contains 10 to 20 wt% solids; the pH of the suspension is adjusted between 10 and 11, pentane and oleic acid are added to the suspension; ag-40 glomerates of phosphates are then formed; the phosphate agglomerates of the 8204749 W ............. · ------ 5 ψ> · ♦ suspension are separated by passing the suspension through a sieve, the phosphate agglomerates in an inert atmosphere heated to remove pentane and then the pentane is recovered from the inert atmosphere and this pentane is recycled.

The present invention can be used to separate all hydrophilic substances from a hydrophobic material. The present invention is particularly suitable for separating gangue minerals from phosphates and for separating ash and pyrite-like sulfur from coal.

The first stage of the present invention is to form an aqueous suspension of the hydrophobic material and hydrophilic substances. Preferably, the suspension has a solids content of 30 to 40% by weight prior to the grinding operation. When there is no grinding step, the suspension should have a solids content of 10 to 20 wt.%.

As an additional preferred step, the hydrophobic material can be ground in the slurry such that the particle size distribution of the hydrophobic material and hydrophilic substances has at least 90% of the particles less than 75 microns in size, more preferably less than 10 microns. Such a grinding step will be used if the hydrophilic substances are also fine-grained. The grinding step helps to release the hydrophilic substances from the hydrophobic material. The grinding step takes place prior to the addition of the coupling hydrocarbon, otherwise agglomerates would form during the grinding and reduce the effectiveness of the grinding operation.

An agglomeration agent is added to the slurry to selectively agglomerate the hydrophobic material. This agglomeration agent is a low boiling, non-polar, water-insoluble hydrocarbon with a boiling point of 70 ° C or less. This agglomeration agent can be butane, pentane, hexane or a mixture thereof. The suspension should contain 10 to 40% of the agglomerating agent based on the weight of the agglomerating agent and the dry hydrophobic material.

The agglomeration agent should be low boiling so that it can be easily recovered at low temperatures and recycled to reduce the need for agglomeration agent. High-boiling hydrocarbons, such as fuel oil, are difficult to recover, even at temperatures of 260 ° C and above. When fuel oil is used as an agglomeration agent, very high temperatures are required to recover the agglomeration agent and these high 40 temperatures are a major handicap for energy needs.

8204749 * ♦ 6

Even at these high temperatures, fuel oil is not fully recovered. For these reasons, low boiling agglomerating agents are preferred over fuel oil. As a general rule, increases in the boiling point of the agglomerating agent cause more difficult recovery of the agglomerating agent, since the agglomerating agent is more adsorbed on the surface of the hydrophobic material.

The agglomerating agent should not be polar for better distribution of the organic product between the aqueous phase and the hydrophobic solid. As the polarity increases, more agglomeration agent is lost in the aqueous phase.

The agglomerating agents should be a hydrocarbon, rather than other non-polar, insoluble agglomerating agents, such as freon, because these hydrocarbons are cheaper than other non-polar agglomerating agents and because downstream halogens can cause problems such as corrosion .

One advantage of using as an agglomerating agent of butane, pentane, hexane or mixtures thereof is that these agglomerating agents result in a greater degree of impurity removal than when using fuel oils.

One other advantage of these low boiling agglomerating agents is that they have lower densities than other agglomerating agents. In the agglomeration, there is an optimum volume of agglomeration agent, which is required to give good, easily separable agglomerates. The energy required to remove the agglomeration agent depends on the weight present. Therefore, when two liquids of equal evaporative heat are used, the energy required to remove equal volumes will be less for the lower density liquid.

When the hydrophobic material is carbon, the agglomeration agent should have a low viscosity to achieve a low ash content in the final product. High viscosity increases the time necessary for agglomerates to form and increases with fuel oils increases the ash and sulfur content of the product.

When an agglomerating agent-free product is desired, the agglomerating agent should be volatile, it should be recoverable at a reasonable temperature (30 ° -70 ° C) and should not be strongly adsorbed in the hydrophobic material. The agglomerating agents of the present invention meet these criteria.

Preferably, the agglomerating agent is added to the suspension 8204749

i - ♦ C

r - ^ .......— - 7 added into a pre-mixer to give a homogeneous feed. In the pre-mixer, a surface conditioner can be added to make the hydrophobic material more hydrophobic (5% by weight or less based on the hydrophobic material and the surface conditioner). Fuel oil is a preferred surface conditioner for oxidized or inferior coal. A high molecular weight organic acid is a preferred surface conditioner for phosphates.

When the slurry is ground, the slurry is diluted to a solids content of 10 to 20% by weight prior to agglomeration.

The hydrophobic material is selectively agglomerated and the hydrophilic substances remain dispersed in the suspension. The hydrophobic material may be subjected to only a low shear agglomeration or in combination with a high shear agglomeration. A low shear agglomeration is sufficient to selectively agglomerate phosphates, but both a high shear agglomeration and a low shear agglomeration are preferred when agglomerating carbon.

When using high shear agglomeration, this should be followed by a period of relatively low turbulence, so that the agglomerates formed in the high shear zone can form a more compact, more easily separable product. The agglomerates exiting the high shear zone are rather small and would cause peeling problems if the subsequent period of relatively low turbulence is omitted.

After the hydrophobic material agglomerates are formed, they can be separated from the suspension by any known separation technique. Preferably, the agglomerates are removed from the suspension using either a sieve or a centrifuge.

A sieve belt is a particularly efficient sieve because of its low cost.

After the agglomerates have been separated from the suspensions, they are heated or evaporated to remove the agglomeration agent. In order to maximize recovery of the agglomeration agent, the product leaving the heated zone should be discarded at a temperature above the boiling point of the agglomeration agent. An inert atmosphere or a vacuum should be used in the heating step to reduce the chance of thermal decomposition of either the hydrophobic 8204 749 8 material or the agglomerating agent.

An advantage of the present invention is that the low boiling agglomeration agents of the present invention do not require high temperatures to be removed, thereby saving energy.

The agglomeration agent can be recovered from the inert atmosphere and recycled. In a method of reclaiming the agglomeration agent, the agglomeration agent and the inert gas are passed through a bag filter for dust removal, then the agglomeration agent and the inert gas are passed through a compressor and a cooler to reclaim the agglomeration agent, whereby the agglomeration agent is recovered from the gas. The gas exiting the cooler is passed through a carbon adsorption system, which further removes agglomeration. The agglomeration agent is then recycled as a source of supplemental agglomeration agent for the pre-mixer and the inert gas is recycled to the heating zone.

Example I

A series of tests were performed using Sunnyside (Utah) coal. In each run, a Sunnyside (Utah) carbon with 5.58 20 wt% ash and ground to a mean particle size of 5.4 micrometers was mixed with water to form an aqueous suspension with 10 wt% solids, an agglomerating agent added to the slurry to form 36 wt.% based on coal and agglomerating agent, the agglomerating agent was used to selectively form agglomerates of carbon and the agglomerates were separated from the slurry and heated in an inert atmosphere to agglomerating agent. When the agglomerating agent was an oil, the coal was extracted with pentane to remove the oils, so that the ash is oil-free. The moisture-free weight percent ash for each 30 'product is shown in the following table.

TABLE A

Effect of agglomeration agent on the ash in the coal Agglomeration agent Wt% ash in product 35 pentane 1.01 gasoline 1.14 terpentina (heavy) 1.35 fuel oil no. 2 1.42 fuel oil no. 4 2.24 40 8204749 F. .........................

9

Therefore, in operation, a low boiling non-polar, water-insoluble coupling hydrocarbon, such as pentane, provides excellent ash removal.

Example II

A series of tests were performed using Pittsburg

Seam cabbage. In each run, a Pittsburg Seam carbon was mixed with water to form an aqueous suspension, the suspension was ground to a specified average particle size, an agglomerating agent was used to selectively agglomerate carbon, the agglomerates were separated from the suspension and the agglomerates were heated in an inert atmosphere to remove the agglomeration material. The anhydrous weight percent ash for each test is shown in Figure 1. The anhydrous weight percent sulfur for each test is shown in Figure 2.

These figures show that the use of a low boiling non-polar water-insoluble coupling hydrocarbon, such as pentane, provides better ash removal and sulfur removal than fuel oil no. 4. These figures also show that the optimal removal of ash and sulfur is reached when the slurry is ground prior to the agglomeration, so that the particle size distribution has an average of less than 5 micrometers.

Example III

An aqueous suspension was formed containing Illinois Cabbage No. 6 with an ash content of 32.92% by weight on a dry coal basis. A No. 4 fuel oil was added to the slurry as a surface-conditioner (oil / carbon weight ratio * 0.033), then pentane was added to the slurry so that the slurry contained 40 wt% pentane based on pentane and dry cabbage. The pentane ward used to selectively form coal agglomerates and the coal agglomerates were separated from the slurry. These agglomerates had an ash content of only 4.10 wt%, which was an ash content reduction of 88%.

Example IV

A series of tests were conducted to demonstrate the effect of the fuel oil concentration on the product ash. In each run, an Illinois cabbage No. 6 was mixed with water to form an aqueous suspension. Fuel oil No. 6 was used at various levels to selectively form agglomerates of coal and the agglomerates were separated from the slurry. The results of these tests are shown in the following table.

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Effect of the oil concentration on the product ash in the agglomeration of Illinois Cabbage No. 6_

Oil weight ratio Weight percent ash in anhydrous 5 to carbon product 0.167 3.17 0.033 2.64 0.017 2.47 0.07 2.01 10 - Therefore, in operation, the presence of increasing amounts of fuel oil in a suspension has an adverse effect on the weight percentage of ash in the end product.

Example V

A series of tests were performed using unweathered phosphate rock from the West. In each run, an un-weathered Western phosphate rock with a particle size distribution such that at least 50% of the particles were less than 400 mesh and containing 20.73 wt% P 2 O (j, was mixed with water under form 20). of an aqueous suspension, the pH of the suspension was adjusted to a special level, oleic acid and hexane were used to selectively form agglomerates of phosphate, the phosphate agglomerates were separated from the suspension and the agglomerates were heated in an inert atmosphere to give the hexane The results of these 25 experiments are shown in the following table.

TABLE B

Effect of the pH on the Ρ20 ^ extraction from non-weathered phosphate rocks from the West_

30 Product quality ^ 2 ^ 5 Waning pH

(wt% P205 (wt%) 30.26 21.2 7.2 28.32 43.0 7.5 35 29.58 42.2 7.9 30.04 46.2 9.1 31.04 76.4 11 .30.09 70.7 11.9 40 Therefore, in operation, the selective agglomeration of phosphate using hexane as an agglomerating agent is an effective agent for the beneficial use of phosphate rock, but such beneficial use serves with a pQ of at least 10 place.

Example VI

Another series of tests was performed to determine the effect of recirculating solvent on the ash content. In each run, an Illinois # 6 coal with 10.87 wt% ash and ground to an average particle size of 3.9 microns was mixed with water to form an aqueous suspension containing 10 wt% solids, the 10 agglomerations conducted with different recycle solvent to carbon weight ratios and in each case, the recycle solvent plus pentane weight percentage was 40% based on carbon, recycle solvent and pentane.

15 Weight ratio of recirculation-% by weight of ash in product solvent to carbon _ 0.3333 3.82 0.1667 3.43 0.0333 2.08 20 0.0233 1.80

Therefore, during the run, as the recycle solvent to carbon weight ratio decreases, the weight percent ash in the product decreases.

In an embodiment of the present invention, small amounts of fuel oil are added to inferior coal to make the coal more hydrophobic. Some carbon products are difficult to agglomerate using only hydrocarbons (gasoline, light fuel oils, eg No. 2, hexane, pentane, etc.) because they have more hydrophilic surfaces. Examples are inferior carbon products (sub-bituminous), carbon products that are oxidized or carbon products, such as Illinois No. 6. In such cases, fuel oils Nos. 4, 5 and 6 or heavy crudes, such as Kern River, may be mixed with the hydrocarbon agglomeration agent to surface of the 35 cabbage more hydrophobic. The fuel oil remains on the product and is not recovered, however, the economic penalty is not heavy because of the small amount of fuel oil used (less than 5% by weight based on dry coal and oil). The agglomerating agent makes up 30 to 40% by weight.

In another embodiment of the present invention, phosphates having a particle size of less than 500 microns are surface-conditioned prior to agglomeration with high molecular weight organic acids at a pH greater than 10 to make the phosphates more hydrophobic. so that they can be separated from gangue minerals such as clays, calcite, dolomite, silicon oxide, etc. The phosphates are conditioned with oleic or other fatty acids or a high molecular weight organic acid with surfactant properties.

The present invention can also be used to recover coal from leftover ponds from a coal-making plant and to recover coal from fine coal circuits from a coal-making plant. Because these fine components are difficult to remove from the process water, these fine carbon components are usually stored in leftover ponds as waste. Since these fines have a significant energy content in the form of coal and since it is expensive to maintain these residual ponds, it will be advantageous to recover these fines as a useful product. This can be accomplished by the method of the present invention.

Also, the present invention can be used in conjunction with short residence time foam flotation to separate metallurgical grade carbon from inferior carbon products and to produce a by-product suitable as fuel for power plants. A metallurgical grade coal and low ash boiler coal are generated by forming an aqueous suspension of coal containing vitrinite, ash and pyrite-like sulfur, by adding a foam flotation reagent to the suspension, by subjecting the suspension to a foam flotation to produce an underflow and an upstream, by filtering and drying the upstream to produce a metallurgical grade carbon, then selectively agglomerating the underflow in such a way that the coal, but not the ash and the pyrite-like sulfur are agglomerated. This selective agglomeration is performed using a non-polar water-soluble coupling hydrocarbon. After the selective agglomeration has taken place, the agglomerates can be separated by a screener or a centrifuge and then the coupling hydrocarbon can be recovered and recycled.

The present invention can also be used to recover carbonaceous components from a liquefied coal frying residue.

8204 74 9 r ^ --...... -....... · .....—- ---. ··· - · - * 13

The low ash carbon agglomerates of the present invention can be used as a feed for a coal liquefaction process. In this embodiment, the carbon agglomerates are subjected to solution in a hydrogen donor solvent to produce a liquid product. When a low ash feed is desired, the agglomerating agent should be a low boiling, nonpolar, water insoluble hydrocarbon fraction from the coal liquefaction process. If a feed with a higher ash content can be admitted, the recirculating solvent is a very economical source of agglomeration agent. U.S. Pat. No. 3,594,304 discloses an effective method of subjecting carbon to solution in a hydrogen donor solvent.

8204749

Claims (15)

A method for separating hydrophilic substances from a hydrophobic material, characterized in that (a) an aqueous suspension of the hydrophobic material and the hydrophilic substances is formed, 5 (b) using a non-polar, in water insoluble coupling hydrocarbon having a boiling point below 70 ° C selectively agglomerates from the hydrophobic material and (c) separates the agglomerates from the suspension containing the hydrophilic substances. Process according to claim 1, characterized in that the head coal hydrogen is recovered and recycled to step (b). 3. Process according to claim 1 or 2, characterized in that a coupling hydrocarbon is used selected from the group consisting of butane, pentane, hexane and mixtures thereof. Process according to claims 1 to 3, characterized in that in step (a) the suspension is formed with a solids content of 10 to 20% by weight. 5. Process according to claims 1 to 4, characterized in that the separation step (c) is carried out using a sieve or a centrifuge. 6. Process according to claims 1 to 5, characterized in that as hydrophobic material carbon and as hydrophilic substances ash and pyritic sulfur are used. 7. Process according to claim 6, characterized in that if an inferior or oxidized carbon is used as carbon, a fuel oil is added to the suspension of step (a) in such a way that the suspension is less than 5% by weight of fuel oil on a dry basis contains coal and oil and the suspension in step (b) contains 30 to 40% by weight of hydrocarbon, based on the weight of the coupling coal hydrogen and the dry coal. Process according to claim 6 or 7, characterized in that the carbon agglomerates are subjected to solution in a hydrogen donor solvent to produce a liquid product. Process according to claim 8, characterized in that the liquid product is recycled as a source of coupling hydrocarbon. Process according to claim 1, characterized in that the hydrophobic material used is phosphate rock, the hydrophilic substances are gangue minerals, the pH of the suspension in step (a) is between 10 and 11 and surface conditioning agent is added to the suspension selected from the group consisting of oleic acids, fatty acids and organic 820 4 74 9 IP ": ....... high molecular weight ganic acids. Process according to claims 1 to 10, characterized in that the suspension of step (a) is ground such that the particle size distribution of the hydrophobic material and the hydrophilic substances is at least 90% of the particles smaller in size than 75 micrometers. Process according to claim 11, characterized in that there is a particle size distribution of the ground hydrophobic material and the hydrophilic substances, wherein at least 90% of the particles are smaller in size than 10 micrometers. Process according to claim 11 or 12, characterized in that the suspension in step (a) has a solids content of 30 to 40% by weight prior to the milling treatment. 14. Process for processing fine carbon products from a coal-making plant, characterized in that an (a) aqueous suspension of fine carbon products is formed, (b) using a non-polar water-soluble coupling hydrocarbon with a boiling point below 70 ° C forms agglomerates of carbon, (c) separates the carbon agglomerates from the slurry, (d) recovers the coupling hydrocarbons and (e) recirculates the coupling hydrocarbons to step (b). Process for preparing a metallurgical grade carbon and a low ash carbon, characterized in that (a) an aqueous suspension of carbon is formed containing vitrinite, ash and pyrite-like sulfur, (b ) adds a foam flotation reagent to the slurry, (c) subjects the slurry to foam flotation to generate an upstream and an underflow, the upstream being rich in vitrinite and having a low content of ash and pyrite-like sulfur and the underflow having a has a low vitrinite content and is rich in ash and pyrite-like sulfur, (d) filters the foam flotation upstream and dries to produce a metallurgical grade carbon, (e) using a non-polar, water-insoluble, head-35 hydrocarbon boiling point below 70 ° C selectively agglomerates from coal from the underflow, (f) separates the coal agglomerates from the underflow containing the ash and the pyrite-like sulfur , (g) the coupling carbon recovers hydrogen and 40 (h) recirculating the coupling hydrocarbon to step (e). 8204 74 9