Differentiation of Barley Genotypes with High Phosphorus Efficiency under Low Phosphorus Stress

[Objective] This study aimed to investigate differences in phosphorus effi-ciency between two-rowed barley and multiple-rowed barley and differences in phos-phorus efficiency among various agronomic traits, and to explore the relationship be-tween agronomic traits and row type with phosphorus efficiency. [Method] Under available phosphorus mass fractions of 1.32 and 36.6 mg/kg, 172 barley varieties, including 79 two-rowed foreign barley, 22 multiple-rowed foreign barley, 58 two-rowed Chinese barley and 13 multiple-rowed Chinese barley, were selected to com-pare differences in phosphorus efficiency-related agronomic traits. Plant height, spike length, number of unfil ed grains, number of unfil ed grains, main panicle weight, to-tal panicle weight, total stem weight, weight of aerial part and heading stage were surveyed for statistical analysis. [Result] The results showed that, various agronomic traits were larger under fertilization condition than under non-fertilization condition ex-cept number of unfil ed grains and heading stage. Plant high, spike length, weight of aerial part and heading stage varied greatly under non-fertilization condition; number of fil ed grains, number of unfil ed grains and total stem weight varied greatly under fertilization condition. In two-rowed barley, plant height and number of fil ed grains of Chinese varieties were higher than those of foreign varieties, while other agronomic traits such as spike length, number of unfil ed grains, main panicle weight, total panicle weight, total stem weight, weight of aerial part and heading stage of foreign varieties were higher than those of Chinese varieties. Spike length and weight of aerial part in multiple-rowed and two-rowed foreign barley were higher than those in Chinese barley. In multiple-rowed barley, plant height, number of unfil ed grains, total panicle weight and total stem weight of foreign varieties were higher under non-fer-tilization condition and lower under fertilization condition compared with those of Chi-nese varieties; number of fil ed grains, main panicle weight and heading stage of foreign varieties were lower under non-fertilization condition and higher under fertil-ization condition compared with those of Chinese varieties. [Conclusion] Heading stage, number of fil ed grains, number of unfil ed grains and total stem weight are more sensitive to phosphorus efficiency. Multiple-rowed barley is more sensitive to phosphorus efficiency than two-rowed barley.

Mixture of ilmenite and high phosphorus iron ore smelted by oxygen-enriched top-blown smelting reduction

In order to reasonably utilize the abundant resources of high-phosphorus iron ore and ilmenite in China, the technology of top-blown smelting reduction with oxygen enrichment was used to smelt the mixed ore of high-phosphorus iron and ilmenite. The effect, which is related to basicity, reduction temperature, carbon-oxygen ratio and time of ventilated oxygen to iron recovery, dephosphorization rate, content of iron, phosphorus, sulfur and titanium in pig iron, was investigated in the experiment. The results show that an ideal outcome can be gained in condition of 6：4 ration on Mengqiao concentrate and Huimin iron ore, temperature of 1 500℃, basicity of 1.3, 1.0 on molar ration of carbon to oxygen, time of 10 min on blowing-oxygen. The outcome is that there is no foamy slag in generation, a good separation of slag and iron, iron recovery with 91.41%, content of phosphorus with 0.27% and tilanium content less than 0.001%, The atmosphere of strong oxidizing in the upper of reduction container and high potential of oxygen in the composition of slag in this technique bring phosphorus, titanium and silicon into slag, which ensures less content of impurity in pig iron.

Effect of coal levels during direct reduction roasting of high phosphorus oolitic hematite ore in a tunnel kiln

The effect of coal levels on phosphorus removal from a high phosphorus oolitic hematite ore after direct reduction roasting have been investigated. Raw ore, coal, and a dephosphorizatiou agent were mixed and the mixture was then roasted in a tunnel kiln. The roasted products were treated by two stages of grind- ing followed by magnetic separation. XRD and SEM-EDS examination of the products was used to analyze differences in the roasted products. The results show that coal is one of the most important factors affect- ing the direct reduction roasting process. When the inner coal levels increased from 0% to 15% the iron grade decreased linearly from 94.94%to 88.81% and the iron recovery increased from 55.94% to 92.94%. At the same time the phosphorus content increased from 0.045% to 0.231%. Increasing the inner coal levels also caused more hematite to be reduced to metallic iron but the oolitic structure of the roasted product was preserved in the presence of high coal loading. The phase of the phosphorus in raw ore was not changed after direct reduction roasting. The effect of coal on the phosphorus content in the H-concentrate arises from changes in the difficulty of mechanically liberating the metallic iron from the phosphorus bearing minerals.

Corrosion and Penetration Resistance of Corundum Bricks to High Phosphorus Oolitic Hematite Reducing Materials

The paper aims at investigating whether corundum bricks can be used for the bottom, of the direct reduction furnace of high phosphorus oolitic hematite. The reducing materials including high phosphorus oolitic hematite, bitumite, Ca（OH） 2 and Na2CO3 at a mass ratio of 1：0. 15：0. 15：0. 03 were mixed and pressed into carbon containing cylindrical specimens with the size of Ф15 mm × 20 mm. The specimens were placed on the corundum bricks and reduced in a high temperature tube furnace at 1 200 ℃ for 40, 60, 80, 140 and 220 min, respective- ly. The corrosion and penetration resistance of corundum. bricks to high phosphorus oolitic hematite reducing materials were analyzed with XRD, SEM and EDS. It shows that the reducing slag formed in the reduction process corrodes the surface of corundum bricks to form a product layer of anorthite and hercynite, retarding the further corrosion of the reducing slag; the reducing slag which has penetrated into the interior of the brick goes through the gaps between the particles and generates anorthite and hercynite, filling the gaps and hindering the reducing slag penetration.

Removal of Phosphorus From High Phosphorus Iron Ores by Selective HCl Leaching Method

The selective HCl leaching method was used to remove phosphorus from high phosphorus iron ores. The hydroxyapatite in high phosphorus iron ores was converted into soluble phosphate during the process of HCl leaching. The effects of reaction time,particle size,hydrochloric acid concentration,reaction temperature,liquid-solid ratio and stirring strength on the dephosphorization ratio were studied. The results showed that the dephosphorization ratio can exceed 98% under the conditions of reaction time 30-45 min,particle size 0.147 mm,hydrochloric acid concentration 2.5 mol/L,reaction temperature 25 ℃,liquid-solid ratio 5：1 and stirring strength 5.02-12.76 s-1. After dephosphorization reaction,the content of phosphorus in iron ore complied completely with the requirements of steel production.

Phosphorus Removal of High Phosphorus Iron Ore by Gas-Based Reduction and Melt Separation

A new method （gas-based separation plus melt separation） has been proposed to remove phosphorus of the high phosphorus iron ore which was 1.25 % of phosphorus content and 50. 0% of iron content. HSC chemistry package and the coexistence theory of slag structure were adopted for theoretical analysis. The gas-based reduction was carried out using a fixed bed reactor and the ore sample of 80 g with an average particle size of 2 mm were reduced using CO or H2 at temperature of 1 073 K for 5 hours. 50 g of the reduced sample with 3.0% CaO as additive was then subjected to melt separation in an electric furnace at temperature of 1 873 K under Ar atmosphere. In each run, SEM, EDS, optical microscopic examination and chemical analysis of the reduced ore sample, the metal sample and the slag sample were conducted. Results of all gas-based reduction experiments showed that iron metallization ratios were some 65% and the phosphorus compounds in the ore remained unchanged. It was agreed well with the simula- tions except for the iron metallization rate being less than predicted value; this difference was attributed to kinetics. Results of melt separation experiments showed that P content in metal samples is 0.33% （metal sample from H2 reduction product） and 0.27% （metal sample from CO reduction product）. The phosphorus partition ratios of both cases were less than predicted values. Some P in the metal samples existed as slag inclusion was considered to be the reason for this discrepancy.

Intensifying Gaseous Reduction of High Phosphorus Iron Ore Fines by Microwave Pretreatment

Gaseous reduction kinetics of the high phosphorus iron ore fines from Hubei in China and effect of microwave pretreatment on the gaseous reduction behavior were studied. Gaseous reduction kinetics were investigated by TG （Thermogravimetric） methods using LINSEIS STA PT 1600 thermal analysis equipment. Microwave pretreatments to the ore fines with four power levels were performed using a high temperature microwave reactor. Its effect was examined by TG methods and its mechanism was analyzed by SEM （scanning electron microscope） and EDS （energy dispersive spectrometer）. Gaseous reduction tests were carried out using a tubular furnace. Results of kinetic study indicate that controlling step of the gaseous reduction of the ore fines is a mixing control of gas internal diffusion and interface chemical reaction when reduction fraction is less than 0.8 and is solid state diffusion when reduction fraction is more than 0.8. Microwave pretreatment of the ore fines could change the pore structure of the oolitic unit to generate cracks, fissures and loose zones, which promotes reduction in the early stage and delays the occurrence of sintering. Gaseous reduction tests show in the condition that the ore fines are pretreated with a microwave power of 450 W for 4 min and reduced under temperature of 1 273 K, the gaseous reduction of the ore fines could be apparently intensified. Using CO or H2 as a reductant and ore fines being reduced for 1.5 to 2 h , increase of metallization rate of the ore fines is 10% to 13%.

Effective removal of phosphorus from high phosphorus steel slag using carbonized rice husk

High phosphorus steel slag and carbonized rice husk are two common wastes characterized by high generation and low secondary use values.Through the reduction of high phosphorus steel slag by biomass,both wastes were fully utilized,thus reducing the negative impact on the environment.In this study,variables such as temperature,time,and amount of reactants were changed to determine the optimal conditions for the reaction of steel slag with carbonized rice husk at high temperatures.The actual amount of reducing agent consumed during the reduction was significantly greater than that predicted by theoretical calculations.Adding three carbon equivalent of carbonized rice husk and maintaining at 1500℃ for 30 min could remove 79.25% of P_(2)O_(5) in the slag.By modeling the material cycle in which high phosphorus steel slag was treated with biomass,the product could be used for crop growth.Meanwhile,the reduced iron and residual steel slag can be used tomake steel again,thereby leading to a sharp reduction in fossil fuel usage and greenhouse gas emissions in this process.

Alum split applications strengthened phosphorus fixation and phosphate sorption in high legacy phosphorus calcareous soil

High phosphorus(P)saturation arising from historic P inputs to protected vegetable fields(PVFs)drives high P mobilisation to waterbodies.Amendment of soils with alum has shown potential in terms of fixing labile P and protecting water quality.The present 15 month pot experiment investigated P stabilisation across single alum application(Alum-1 treatment,20 g alum/kg soil incorporated into soil before the maize was sown),alum split applications(Alum-4 treatment,5 g alum/kg soil incorporated into soil before each crop was sown i.e.4×5 g/kg)and soil only treatment(Control).Results showed that the Alum-1 treatment caused the strongest stabilisation of soil labile P after maize plant removal,whereas the P stabilisation effect was gradually weakened due to the transformation of soil non-labile P to labile P and the reduced active Al^(3+)in soil solution.For the Alum-4 treatment,soil labile P decreased gradually with each crop planting and was lower than the Alum-1 treatment at the end of the final crop removal,without any impairment on plant growth.The better P stabilisation at the end of Alum-4 treatment was closely correlated with a progressive supply of Al^(3+)and a gradual decrease of pH,which resulted in higher contents of poorlycrystalline Al,Fe and exchangeable Ca.These aspects were conducive to increasing the soil P stabilisation and phosphate sorption.In terms of management,growers in continuous cropping systems could utilise split alum applications as a strategy to alleviate P losses in high-P enriched calcareous soil.