Ironmaking Using Municipal Solid Waste (MSW) as Reducing Agent: A Preliminary Investigation on MSW Decomposition and Ore Reduction Behavior

Abstract

The iron and steel industries currently face the depletion of high-grade ore and high CO₂ emissions. Some initiatives that effectively utilize alternative carbon sources and abundant low-grade ores become the preferable solutions. This novel study aims to utilize municipal solid waste (MSW) as a reducing agent in ironmaking using low-grade (goethite) ores. As an initial fundamental approach, the comparison of decomposition behaviors between the model and actual MSW was investigated in thermogravimetric analysis. Both model and actual MSWs mainly decompose at 300–500°C. As for reduction tests, pellets containing MSWs and ores with different pretreatments were prepared. The pellets were reduced in an Ar atmosphere at different temperatures. The effect of different ores: high-grade and low-grade ones, on the decomposition of MSW and the iron reduction, were investigated. As a result, interestingly, the low-grade, goethite ore-containing pellet exhibits a more significant reduction degree than the high-grade ones. The reduction is completed in 5 minutes at 700°C and above, indicating a significant reduction by the decomposed carbon. The reduction degree extends at elevated temperature, which reaches more than 94% at 900°C.

1. Introduction

Ironmaking and steelmaking are now facing major problems with their sustainability to meet the global steel demand, which is expected to rise to 2.5 billion tons per year by 2050.¹⁾ Those three major problems are the depletion of coking coal and high-grade ore as raw materials, high CO₂ emission, and intensive energy use. One solution is to introduce alternative reducing agents replacing the depleted non-renewable coke or natural gas and reducing CO₂ emission to meet the Paris Agreement 2015. Although hydrogen-based ironmaking has become the most prospective solution to apply,²⁾ carbon sources are still necessary for steel production.³⁾

Meanwhile, municipal solid waste (MSW) is becoming a major environmental concern considering population growth and urban social-economic development.⁴⁾ A typical MSW contains waste food, plastic, textile, rubber, and other non-combustible materials.⁵⁾ Generation of municipal solid wastes (MSW) with massive amounts represents a big problem for many countries, which the total worldwide would reach up to 3.4 × 10⁹ tonnes in 2050.⁶⁾ Also, transportation and disposal of these amounts are land and resources consuming so managing these wastes has become an urgent issue recently.⁷⁾ Although MSW has a potential risk for human health and the environment, it is gradually considered one of the most renewable resources to convert into energy, materials, fuel, and higher-value byproducts.^{8,9,10,11,12,13)} A typical MSW has around 9.1 MJ/kg of low heating value (LHV).¹⁴⁾ The well-dried MSW has a higher heating value (HHV) of up to 21 MJ/kg, potentially similar to sub-bituminous coal.¹⁵⁾ The carbon content in MSW can be promising for reducing agent and carbon source in further steelmaking.

On the other hand, instead of the high-grade hematite ore, the abundance goethite (FeOOH)-based ore, which is low-grade ore, is also necessary to consider to be utilized for future ironmaking.¹⁶⁾ As dehydrated to remove its high combined water (CW), goethite changes to nanoporous hematite.¹⁷⁾ The previous studies reported that when dehydrating goethite at 200–250°C,^18,19) slit-like pores with a width less than 2 nm are generated.²⁰⁾ The pore generation can be even faster in vacuum conditions.²¹⁾ However, its brittleness can cause permeability problems when it is directly used in the existing ironmaking process like blast furnace^17,22,23) or direct reducing process.¹⁷⁾ Nevertheless, as counter merit, this generated nanopore can promote a significant improvement in its reduction reactivity^24,25) as well as its catalytic activities for fuel decomposition.^26,27,28,29) This merit is due to the closer contact between iron oxide and reducing agents such as C, CO, or H₂.^30,31,32,33)

Various techniques to prepare the close contact carbon and ore in pellets or composite have been proposed by pelletizing,^32,33,34,35) or chemical vapor deposition,^27,36,37,38) has become promising approaches utilizing various carbonaceous fuel materials (i.e., coal, woody-biomass, polyethylene) for lowering the reduction temperature in ironmaking.³⁹⁾ However, investigation on co-utilization of MSW and low-grade ore for ironmaking has never been done before. Therefore, this novel study aims to utilize municipal solid waste (MSW) as raw material for ironmaking reducing agents, investigating the decomposition and reduction behavior of pellet composites containing MSW and iron ores as a fundamental approach. The pellet decomposition behaviors between the model and actual MSW pellets with the iron ore’s absence and presence were compared. The effects of different aspects of the pellet preparations on MSW decomposition and iron reduction were preliminarily investigated.

2. Experimental Methods

2.1. Materials and Pretreatment

2.1.1. Iron Ores

This study used two types of ores: an Australian low-grade, high combined water-containing ore (Ore A) and a Brazilian high-grade ore (Ore B). The properties of the materials are listed in Table 1. The raw ores were crushed and sieved to a particle size range of 0.6–1.0 mm.

Table 1. The properties of ore A and B used as raw materials in this study.

Ore samples	Type	CW [wt%]	T.Fe [wt%]	FeO [wt%]	SiO2 [wt%]	Al2O3 [wt%]
A	Low-grade (Geothitic)	6.36	61.92	0.14	2.83	1.73
B	High-grade	0.77	64.99	0.1	4.68	0.98

Both ores were then dehydrated by heating at 300°C, ramped at 10°C min⁻¹, held for 1 h in a vacuum condition (P = −100 kPa) as the similar preparation method in the previous study²¹⁾ to quickly remove the combined water. There was no change in the particle size of the ore after dehydration. The ores A and B with dehydrated and raw samples were prepared to investigate the effects of dehydrated and undehydrated ores on the MSW decomposition and ore reduction.

2.1.2. Municipal Solid Waste

The municipal solid waste samples (MSW) were used in this study. The actual MSW samples were collected from the final waste disposal site, TPA Piyungan, Yogyakarta, Indonesia. The actual MSW typically consists of food waste, plastic, wood, paper, and textile with a weight composition ratio of 55.86, 11.15, 2.94, 8.52, and 3.16, respectively. Since the properties of the actual MSW might vary from different sources, a model of MSW was also prepared for comparison. The model MSW was prepared by combining fine starch, polyethylene reagent, pine sawdust, and distilled water with the weight ratio of 1:1:1:2 to replicate food, plastic, wood waste, and water (moisture) content in a typical MSW composition, respectively. The properties of each material are shown in Table 2. Since the model MSW is more accessible to prepare than the actual one, we first investigated its decomposition and ore reduction behaviors, then set up experimental parameters for using the actual MSW based on the model MSW finding.

Table 2. The properties of each component in the model and actual MSW used as raw materials in this study.

MSW Samples		Proximate [wt%]				Ultimate [wt%]
		VMa	FCa	Asha	TMb	Cc	Hc	Nc	Od	C/O ratio	H/O ratio
Model	Starch	77.2	5.0	5.0	12.8	39.88	6.13	<0.30	54.02	0.74	0.11
	Polyethylene	99.9	0.0	0.1	0.0	84.9	14.5	0.00	0.00	inf	inf
	Pine Sawdust*	81	18.6	0.4	0.0	49.83	6.18	<0.30	43.99	1.13	0.14
	Mixed MSW**	83.1	12.0	2.0	2.9	58.20	8.94	<0.30	32.67	1.78	0.27
Actual	Food Residue	77.8	14.2	7.5	0.5	41.06	5.28	1.25	52.41	0.78	0.10
	Plastic	86.3	0.0	11.5	2.2	71.89	11.57	<0.30	16.25	4.42	0.71
	Wood	77.0	15.8	4.8	2.4	28.11	3.00	1.12	67.76	0.41	0.04
	Paper	80.7	9.3	6.9	3.1	44.9	6.17	<0.30	48.68	0.92	0.13
	Textile	66.0	8.3	24.4	1.3	49.66	3.54	0.33	46.47	1.07	0.08
	Mixed MSW***	64.6	10.1	22.7	2.6	47.12	5.91	0.54	46.31	1.02	0.13

^a  VM, ash, and FC = volatile matter, ash content, and fixed carbon, respectively.

^b  TM = total moisture (%, as-received basis).

^c  C, H, and N = carbon, hydrogen, and nitrogen contents, respectively.

^d  O = oxygen content calculated by difference.

*  As reported in.³⁷⁾

**  Mixed at Starch:Polyethylene:Pine Sawdust = 1:1:1 based on¹⁴⁾ at dry basis.

***  Mixed at Food Residue:Plastic:Wood:Paper:Textile = 55.86:11.15:2.94:8.52:3.16 based on typical raw MSW in¹⁴⁾ at wet basis.

2.2. Pellets Preparation

The MSW and ore samples were mixed using a mortar with the MSW to ore weight ratio of 5:1. Around 1.8 g of the mixture sample were packed in a pellet die sleeve (diameter and height of 10 mm and 40 mm, respectively) and pressed at 50°C for 10 minutes at a specified pelletizing pressure. The heights of the prepared model and actual MSW pellet were in the range of 16–18 mm and 8–10 mm, respectively. The addition of the ore into the pellets under the particular amount did not change the pellet height. The pellets were then dried at 60°C overnight before the reduction test. Several effects were investigated by varying parameters such as the types of MSWs, ore types with dehydration, and the pelletizing pressure.

2.3. Thermogravimetric Experiments

Thermogravimetric (TG) curves were obtained by pyrolysis experiments using a Mettler Toledo DSC-1. The sample of around 20 mg weight was put in 150 µl alumina crucible. The experiments were conducted in a transient temperature condition, which varied from 25 to 1000°C with a constant heating rate of 5°C min⁻¹, and an argon flow (100 Nml min⁻¹) was continuously maintained. The obtained data were then analyzed to investigate the thermal decomposition behavior of different components in both models and actual MSW samples.

2.4. Reduction Experiments

A prepared pellet sample was cut to a predetermined mass and then reduced in the apparatus shown in Fig. 1(a). The pellet was placed in a quartz tube reactor (17 mm of ID, 750 mm of length) with quartz wool of approximately 0.1 g put as the bed support. A thermocouple for the programmed temperature was placed inside the quartz tube below the bed support. The reactor was heated under Argon flow at 200 Nml min⁻¹ in a vertical electric furnace at its maximum ramp to different final temperatures (700–900°C). Figure 1(b) shows the bed temperature profiles during heating, indicating the apparent heating rate is approximately 80 K min⁻¹. A preliminary test was also conducted to confirm no temperature disparity at the different axial positions around the pellet.

Fig. 1.

(a) Schematic figure of pellet reduction experiment. (b) Temperature profiles during the pellets reduction experiments under maximum ramp heating up to different final temperatures. (Online version in color.)

The exhaust gas concentrations of the outlet gases, such as H₂, CH₄, CO, CO₂, and H₂O, were analyzed online using quadrupole mass spectroscopy (QMS200, Pfeiffer), as the similar method in our previous study.²⁵⁾ The molar flowrates of each gas were calculated using   

$${\dot{n}}_i=f_T\cdot \frac{C_i}{100}\cdot \frac{{10}^3}{24.0548}$$(1)

where ${\dot{n}}_i$ is the calculated molar flowrate of each components i (i.e., H₂, CH₄, CO, CO₂, H₂O) [mmol min⁻¹]. C_i is the gas concentration of each component i measured by QMS200 [mol%]. f_T is the total volumetric flowrate in the reactor outlet gas [Nml min⁻¹]. The factor of $\left(\frac{{10}^3}{24.0548}\right)$ is the conversion factor of gas volumetric flowrate to molar flowrates at NTP - Normal Temperature and Pressure - condition [mmol Nml⁻¹]. The NTP condition is defined as air at 20°C (293.15 K) and 1 atm.

In order to investigate the suitable conditions under which reduction can quickly occur, the experiments were conducted under different pellet preparation methods.

2.5. Samples Characterizations

Characteristics of the samples before and after the reactions were analyzed using X-ray diffractometry (XRD, Miniflex, Rigaku). The reduction degree (RD) of each sample was then calculated using   

$$RD=\frac{mass\mathrm{\hspace{0.17em} }of\mathrm{\hspace{0.17em} }removed\mathrm{\hspace{0.17em} }oxygen}{mass\mathrm{\hspace{0.17em} }of\mathrm{\hspace{0.17em} }removable\mathrm{\hspace{0.17em} }oxygen}\times 100\%$$(2)

However, it was not easy to evaluate the exact amount of removed and removable oxygen because gangue materials such as SiO₂, Al₂O₃, and other oxides might be different within the ore samples. The RD of each sample was then calculated based on the composition of iron oxides in the sample using   

$$RD=\sum x_{i}R{D}_i$$(3)

where x_i is the mass fraction of iron oxide component i (i = Fe₂O₃, Fe₃O₄, FeO, or Fe) in the sample from the composition of oxide structure adapting the reference intensity ratio (RIR) methods.⁴⁰⁾ x_i is the weight fraction of component i according to the intensity of X-rays diffracted by the component’s selected plane (hkl). RD_i is the reduction degree of the different iron structures, where RD_i of Fe₂O₃, Fe₃O₄, FeO, and Fe, are 0%, 11%, 30%, and 100%, respectively.

The samples before and after reduction were also analyzed using scanning electron microscopy (SEM, JEOL, JSM-7001FA) equipped with energy dispersive spectroscopy (EDS) to evaluate their morphology and elemental distribution mapping of Fe, C, and O.

3. Result and Discussions

3.1. Thermal Decomposition of MSW

Figure 2 shows the TG and DTG results for each component in the model and actual MSWs. The MSW mass decreases significantly at 300–500°C. The results show that the thermal decomposition of MSW starts around 300°C and is completed by 500°C. In addition, in the actual MSW, the decomposition continues at above 700°C in the case of food waste. This phenomenon is probably due to the lignin content in the sample decomposing over 700°C, as similarly reported in other studies.^41,42)

Fig. 2.

Thermogravimetric (TG) and differential thermogravimetric (DTG) curves representing the comparison of the thermal decomposition behaviors between each component in MSW samples: (a) model MSW and (b) actual MSW. (Online version in color.)

Figure 3 compares the mass change of pellets for the model and actual MSW in the present with and without iron ore. The masses at any temperature in both figures were normalized to the selected reference temperature of 500°C to distinguish the thermal decomposition of MSW and ore reduction. The mass loss at a temperature below 500°C mainly remarks as thermal decomposition. In contrast, the extent loss above 500°C is due to the ore reduction. In the case of model MSW, it clearly shows that the pellet with ore extends to decrease its mass at above 750°C, indicating that the ore reduction starts around this temperature. This result corresponds to other kinetic reports mentioning that the composite of biotar-derived coke and limonite ore shows a higher reduction reactivity than conventional coke because of the high reactivity of biotar-derived coke and their nanoscale contact.^24,27) However, in contrast, in the case of actual MSW, the mass loss corresponding to lignin still occurs even at high temperatures, causing not clearly distinguishing on what temperature the ore reduction occurs. Hence, a single pellet reduction test with an evolved gas analysis was also conducted to clarify this finding.

Fig. 3.

Comparison between the weight changes of the pellets samples with and without dehydrated ore A using (a) model MSW and (b) actual MSW cases. The weight changes were adjusted to each sample weight at 500°C to distinguish the MSW thermal decomposition and ore reduction behaviors. (Online version in color.)

3.2. Evolved Gas Analysis during Reduction Test

Figure 4 shows the CO and CO₂ evolved gas analysis when the model and actual MSW pellets containing dehydrated ore A are reduced in a quartz tube reactor set. The reaction temperature was set to 900°C, and the amount of CO and CO₂ gases generated per gram of reacted MSW was analyzed. The peaks at temperatures below 500°C are mainly due to the pyrolysis of MSW. In contrast, the peaks at 700°C above, present in the pellets with ore, are beyond the MSW thermal decomposition range and can be attributed to reduction. The peak in the high-temperature zone is mainly due to CO. The reduction of the ore proceeds according to either of the reaction equations shown below.   

$$\mathrm{F}{\mathrm{e}}_{\mathrm{x}}{\mathrm{O}}_{\mathrm{y}(\mathrm{s})}+\mathrm{y}{\mathrm{C}}_{(\mathrm{p}\mathrm{y}\mathrm{r}\mathrm{o}\mathrm{l}\mathrm{y}\mathrm{t}\mathrm{i}\mathrm{c},\mathrm{s})}\to \mathrm{x}\mathrm{F}{\mathrm{e}}_{(\mathrm{s})}+\mathrm{y}\mathrm{C}{\mathrm{O}}_{(\mathrm{g})}$$(4)

  

$$\mathrm{F}{\mathrm{e}}_{\mathrm{x}}{\mathrm{O}}_{\mathrm{y}(\mathrm{s})}+\mathrm{y}\mathrm{C}{\mathrm{O}}_{(\mathrm{g})}\to \mathrm{x}\mathrm{F}{\mathrm{e}}_{(\mathrm{s})}+\mathrm{y}\mathrm{C}{\mathrm{O}}_{2(\mathrm{g})}$$(5)

In the reaction Eq. (4), CO is generated by the reaction in which carbon directly consumes oxygen from the iron oxide in the ore, known as direct-carbon reduction. In contrast, in Eq. (5), CO₂ is generated by the reaction in which CO consumes the oxygen from the iron oxide, well-known as the indirect reduction. In the process of this study, the carbon from decomposed MSW actively acts as a reducing agent, as the reaction in Eq. (4). Meanwhile, the reaction in Eq. (5) is an indirect reduction probably because CO is generated from the reaction in Eq. (4).

Fig. 4.

CO and CO₂ evolved gas analyses during reduction at 900°C of different pellets: (a) model MSW only, (b) actual MSW only, (c) model MSW pellet with ore A(DH), and (d) actual MSW pellet with ore A(DH). (Online version in color.)

The reduction behaviors of the pellets are related to the C/O and H/O values in MSW samples. The model MSW with ore A(DH) mixture has C/O and H/O values of 1.36 and 0.21, respectively. In comparison, the actual MSW-ore mixture has smaller values of 0.84 and 0.10, respectively. The C/O values on both samples are significantly higher than the H/O, meaning the thermal decomposition and reduction process generate more carbon-oxide gases (i.e., CO and CO₂). The smaller C/O value of the actual MSW sample, in particular, indicates the actual MSW has more oxidative behavior resulting in more CO₂ from its decomposition. This effect can be seen in the case of the actual MSW pellet with ore A(DH), whereas the peak of CO₂ gas at 500°C is higher than the CO gas.

Figure 5 shows the gas generated from gas analysis results when model MSW and actual MSW pellets and pellets containing ore A are reduced. The reaction temperatures were set up to 700, 800, and 900°C, and the accumulated amount of gas generated per gram of reacted MSW at each temperature was determined. In the case of both the model and actual MSW, there was no significant difference in the reduction of pellets without ore in response to the elevating temperatures. This is because pyrolysis is already completed by 500°C. In contrast, in reducing pellets containing ore, CO generation increases at elevated temperatures. This increased amount of gas is generated at 700°C or higher due to the ore reduction. This result is also consistent with the result in Fig. 4. As the temperature was increased, the amount of CO generated increased, while the amount of CO₂ generated did not increase, confirming that the reduction reaction is a carbon-direct reduction.

Fig. 5.

Cumulative gas amount generated from the reduction of the pellets at different temperatures. (a) Model MSW pellet, (b) Actual MSW pellet, (c) Model MSW pellet with ore A(DH), and (d) Actual MSW pellet with ore A(DH). (Online version in color.)

3.3. Reduction of Different Ores and Conditions

Figure 6 shows the comparison between ores A and B in the prepared pellets using model MSW at different pretreatment (dehydration) conditions, before and after reduction tests. The pellet was prepared at 30 MPa of pelletizing pressure. After reduction at 900°C for 20 min, ore A has significant RD compared to ore B. Moreover, the dehydrated ore A exhibits higher RD. Ore A contains more goethite, which has more CW. Our previous study found that dehydration of goethite significantly generates nanopore contributing to a larger surface area for reaction.^19,20,21) The carbon from the MSW is probably deposited in the pores, reducing the distance between ore and carbon and facilitating significant reduction. Remarkably, ore A is more suitable as the iron ore materials to be used in this process.

Fig. 6.

(a) XRD patterns of ore A at different dehydration and reduction conditions. (b) XRD patterns of ore B at different dehydration and reduction conditions. (c) Calculated reduction degrees of the reduced ores based on the results of (a) and (b). (Online version in color.)

Figure 7 shows the SEM images and EDS mapping results of the dehydrated Ore A and B before and after reduction under the same conditions corresponding to Fig. 6. Comparing the EDS mapping of the samples after reduction, the pellet containing ore A shows less overlapping of Fe and O, meaning it has more progressive reduction than the one containing ore B. It is also consistent with the results in Fig. 6. In addition, the particle size of the ore is more suitable in ore A. It is probably because the dehydration of ore A creates more porosity, which reduces the strength of the ore and makes the ore easier to crush during the pellet preparation and reduction. The finer the ore, the closer contact between the ore and carbon, thus promoting a more significant reduction to proceed. In addition, in both cases, the overlapping C and O on the samples before reduction can be interpreted as the presence of organic carbonaceous material (i.e., biomass) in the pellet sample. After the reduction, it is confirmed that less or even no O was detected, meaning that all carbonaceous material in MSW became only carbon due to pyrolysis.

Fig. 7.

SEM images and EDS mapping of Model MSW pellets containing (a) ore A(DH) before reduction, (b) ore A(DH) after reduction, (c) ore B(DH) before reduction, and (d) ore B(DH) after reduction. (Online version in color.)

3.4. Reduction of Different Temperature and Time Conditions

Figure 8 shows the reduction degree obtained from the XRD results of the samples that reduced the model MSW and actual MSW pellets containing Ore A. The reduction temperatures were set at 700, 750, 800, and 900°C with varying reduction times from 0 to 40 min. The pressure applied during pellet making was 30 MPa. When comparing the model MSW and actual MSW, the model MSW showed a more progressive reduction overall. This is due to the particle size of the substance composing the model MSW being smaller than the actual MSW. In this case, the carbon and ore are in closer contact with each other. In the case of both MSWs, the higher the temperature, the higher the reduction degree. It could reach an RD of over 94% at 900°C. In addition, there is a slight change in the reduction degree after 5 minutes at all temperatures. This result indicates that the reduction progresses significantly faster at higher temperatures.

Fig. 8.

The comparison between the reduction degrees of (a) the model MSW pellet with DH A ore and (b) the actual MSW pellet with DH A ore at different reduction times and temperatures. (Online version in color.)

3.5. Reduction of Different Pelletizing Pressures

Figure 9 shows the reduction degree obtained from XRD of the samples of the model and actual MSW pellets containing dehydrated ore A at 750, 800, 850, and 900°C without holding time. The investigation was conducted by varying the pelletizing pressures of 30, 50, and 100 MPa. As a result, the higher the pressure applied during pellet preparation in model MSW pellets, the higher the reduction degree. The distance between the ore and carbon significantly affects the extent of reduction since the overall reduction process is predominated by direct reduction by carbon. Applying more pelletizing pressure can provide a closer contact, decreasing the reduction temperature. However, in contrast, there are no significant changes in the reduction degree of the actual MSW pellets samples at higher pelletizing pressure, suggesting that for iron reduction, the actual MSW pellets were sufficiently prepared at the pelletizing pressure of 30 MPa.

Fig. 9.

The comparison between the reduction degrees of (a) model MSW pellet with ore A(DH) and (b) actual MSW pellet with ore A(DH) at different pelletizing pressures. (Online version in color.)

Although this study was still preliminary, it revealed one promising solution for iron and steelmaking that could be combined with MSW treatment. This approach could set off a new perspective in the related research field. In particular, hydrogen-based ironmaking still requires carbon to produce steel. That required carbon is possible to be supplied from the remaining carbon in the MSW pellet after reduction. On the other hand, the metallic iron in this process needs to be separated from its slag, which will remain in future studies. Also, further investigations are necessary to be conducted to find feasible applications based on this study, such as kinetic study, process design, and overall evaluation through life cycle analyses (LCA) on material and energies.

4. Conclusion

MSW has promoting potential as a reducing agent for ironmaking. This novel study has successfully demonstrated the reduction behavior of the low-grade ore using MSW as a reducing material. The following conclusions have been reached so far:

(1) MSW thermally decomposes to solid carbon and gasses. Then the ore reduction occurs mainly by the reaction of C removing oxygen from iron oxide in the ore to become CO, which is a direct reduction.

(2) The low-grade ore with high combined water content (ore A) is more suitable as a raw material in this process.

(3) The iron ore could be rapidly reduced in 5 min. The higher the reduction temperature, the more the reduction progressed, with more than 94% reduction at 900°C.

(4) Since direct reduction by carbon is dominant, the higher the pressure applied during pellet preparation, the more the reduction progresses, and the lower the reduction temperature can be achieved. In addition, the pellet pressing at 30 MPa was sufficient for an actual MSW case.

This preliminary investigation revealed a new attractive potential of MSW utilization in ironmaking, which could simultaneously solve the waste problem in society.

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